Improving and modifying a Jimny for mixed road and all terrain use

Introduction

[this entire article is still in the making - more changes and additions are planned to be written]

A Jimny in factory stock form is quite capable vehicle for all terrain use, and "okay" for on-road use (depending on your on-road needs and preferences).

However, as every vehicle, it has its weak points and potential for improvement in areas where the manufacturer skimped (or made an oversight) during design or construction phase.

Also, there are some improvements and modifications which go "beyond" the vehicle's mechanical design "contours", but they make a significant improvement for certain usages.

Jimnys can be extensively modified to the extent of being unrecognizable, but the expense will be twice as much as a brand new Jimny, and the vehicle will be no good for anything except for rolling in the mud or over rocks.

However, if the vehicle needs to be used in mixed conditions (on road, city, highway, job, family, and all kinds of all terrain use), the goal is just to improve it and modify it "sensibly" - while staying within the legal boundaries and within the logical/practical usage boundaries that will satisfy all of those usage conditions.

In accordance with that mixed usage criteria, here are the most common points of improvement and modification for Jimnys (in no particular order of importance):

1. Tyre size

An entire encyclopedia can be written on tyre sizes. This is only a quick and rough summary.

The factory tyre size on Jimnys (except for some "JDM" models in Japan) is 205 / 70 / R15.

The three most popular, non-extreme size upgrades are to:

1. 205 / 75 / R15 (ground clearance and tyre's sidewall height increase by cca. 10 mm)
2. 195 / 80 / R15 (ground clearance and tyre's sidewall height increase by cca. 13 mm)
3. 215 / 75 / R 15 (ground clearance and tyre's sidewall height increase by cca. 18 mm)

However, they may impose certain risks of collisions between tyres and the vehicle body in some vehicle configurations. That mostly depends if the vehicle has 2nd gen. front bumper or not, if it has front mudflaps or not, if wheel spacers are used, etc. The risk is the lowest with the first size in the list, and the highest with the third size in the list.

They will also introduce certain deviations in vehicle's driving characteristics (road handling, acceleration, top speed, engine braking, transmission's stress). However, those deviations range from "negligible" to "small". The first size in the list is the least deviant, as it provides the smallest diameter change, while also keeping the same tyre width.

Bear in mind that while the first size might be allowed by Suzuki (depending on company's regional policy), the second and third sizes are definitely not allowed by Suzuki. Also bear in mind that ANY tyre sizes apart from those which are strictly specified in vehicle's handbook are prohibited in certain countries!

Regarding "tyre vs. vehicle body" collision risks:

Sizes 205 / 75 / R15 and 195 / 80 / R15 generally have no risks of collisions, with two exceptions:

• If you have a 2nd gen. front bumper (see below), you might have to straighten it if it is sagged, or trim it just slightly (invisibly) on the bottom (simple job with a grinding tool).
• If you have front mud flaps, you might have to trim a plastic spacer behind them by approx 10-15 mm (which is easy to dismount and mount).

Size 215 / 75 / R15 could be more problematic:

• It may require some trimming of the bottom of the front bumper, especially if it is a 2nd gen. bumper.
• Front mudflaps will probably need to be removed.
• The spare tyre might contact with the rear bumper.
• Wheel arch trimming is generally not needed, except if wheel spacers are used without a lift.

Warning: "Remouled" (retreaded) tyres typically deviate significantly from their theoretical sizes (they tend to be quite larger)!

This was a quick and simple guide to the issue of tyre sizes.

On the other hand, if you want to dig neck deep into the issue, study the table on Jimny-compatible tyre sizes, which was made by forum user Bosanek: [1]

2. Tyre model

Another encyclopedia can be written about proper tyre models. However, for general mixed use, a simple, versatile and quite satisfactory solution is a good all-season AT class tyre model.

Two AT tyre models with which people have had great experiences on Jimnys are Goodyear Wrangler AT/SA+ and General Grabber AT (not AT2!).

Also, General has recently (09/2016) released model AT3, which looks very interesting. Avoid the model AT2, it is very old and deprecated one!

If you insist on heavy-duty off-road performance but still want to retain some on-road credibility, there are three MT class tyre models with which Jimny owners have been relatively satisfied with: Bfgoodrich Mud-Terrain T/A KM2, Hankook Dynapro MT (RT03) and Kumho Road Venture KL71.

There are other good AT and MT tyre brands and models of course.

Here is Bosanek's list of all brand-name HT, AT and MT tyre models which he has found on the market, including size availability in Jimny-usable sizes: [2]

A lot of time has been spent populating that list, and adding custom remarks there. The list is still incomplete in some details, but will be updated from time to time.

Note: Not all of those tyre models in the list are available in sizes which are compatible for Jimny.

3. Five identical tyres

Buy and use five same (identical) tyres! The spare tyre should not sit idle all the time! That is even written in Jimny's owner manual.

The spare tyre should be actively rotated with the other four. In case of an all-terrain vehicle like the Jimny, that gives you so much benefits, and only one downside - you pay 25% more at once.

Here is Bosanek's document which shows the rotation scheme, and also lists "FOR" and "AGAINST" reasons to actively use all five identical tyres in a 5-tyre rotation scheme: [3]

Is is a handy practice to rotate the tyres with every motor oil change. If you recently bought a set of four new identical tyres (they have not got worn more than 1-2 mm at most), you still have plenty of time to buy the fifth one (you don't need it yet, until the first rotation).

Warning: If you have a hard or soft spare wheel cover, you won't be able to use it with a spare tyre which is larger than the stock size.

4. Tyre pressures

Learn and use the skills of tyre pressure management.

Changing your tyre pressures to suit the (off)road conditions is the most effective vehicle mod ever! The benefit is not just for improved traction, but also for improved ride comfort and reduced vehicle stress!

In general terms, reducing tyre pressure by 20-30% from stock on-road pressure is the operating norm for hard gravel and general off-road conditions. For deep mud, deep snow, sand and other boggy conditions, even more pressure reduction can be used (but with caution).

So, for a Jimny, the stock tyre pressure is 1,6 bar front and 1,8 bar rear (some people even it to 1,7 bar on all four tyres). When driving on gravel roads or general off road, it is OK to reduce the tyre pressure by 25-30% to 1,25-1,15 bar - the difference in ride quality is astonishing, while the traction is significantly improved.

Warning: When tyre pressures are reduced, vehicle's top speed should be limited to approx 50 km/h on tarmac roads (40 km/h on gravel roads). Otherwise, the tyres might overheat and fail prematurely!

It is compulsory to carry a good quality tyre pressure measurement tool, and very desirable to have your own 12V air compressor. You can inflate your tyres at gas stations (their equipment is much quicker than your own compressor), but never trust the pressure measurement instruments at gas stations, as they can be wildly inaccurate!

5. Underbody protection guards

Install aftermarket-made metal guards for the radius arm mounts, the transfer box and the rear shock absorbers. They will pay of with VAT the first time they get hit!

Even if you don't do hardcore offroading, you are going to hit a rock sooner or later - it's just a question of a moment when you lose your concentration for that tiny amount of time.

6. Underbody rust protection

Clean the rust from the underbody of the vehicle (if it has rust), and then protect the underbody against future rusting with some good anti-rust material.

There are several schools of thought of which materials and methods should be used to achieve anti-rust protection.

Some use coatings ("underseals") like bitumen. However, these coatings can hide the rust behind them if the surfaces are not thoroughly cleaned prior to coating application, or if the coating has not been thoroughly applied, so the moisture "creeps" under.

One alternative method is to apply "rust inhibitors". Most of them work on the principle of chemically altering the rust itself, "freezing" it or chemically converting it into another substance. They are usually quite expensive, and typically do not have an effect on non-rusted surfaces (rust must first appear, and then you apply the inhibitor).

There are other alternative methods and substances. Explore on your own.

One of many manufacturers of products which deal with rust is Buzzweld.

7. Tie rod ends

If Jimny is regularly used on gravel or off road, original (OEM) tie rod ends typically prove significantly more durable than aftermarket ones.

Since wheel alignment has to be performed (and paid for) after each tie-rod end change, it definitely pays off to use the best ones - OEM!

8. Steering damper (shock absorber)

This is one area where you can do a good deed to your vehicle, no matter where you drive it.

All serious all terrain vehicles have factory installed steering dampers. Suzuki's vehicles do not, although they need it badly because they are so bumpy and twitchy. Suzuki probably skimped on that for cost reasons.

If you install a steering damper, it will significantly improve the steering feel. The steering in a Jimny is generally very light. With a steering damper, it will feel heavier in a positive sense (like you are driving a proper big 4WD vehicle), but will not be hard.

Also, vehicle's "twitchy" behavior at dodgy tarmac roads will be significantly softened, and the shake while driving on gravel roads will be significantly cushioned.

There are several steering dampers available around, which can be utilized on a Jimny. If you don't want anything flashy, the ordinary steering dampers made for Land Rover Discovery 1 have been found to be quite satisfactory, and they are usually cheap to buy online. One such steering damper is Armstrong STC786.

Since Jimny has no mounts for the steering damper, there are several "bolt on" kits available to buy, but you can also weld on your own pieces of metal to make the mounts if you have that skill and do not mind to "burn" the vehicle.

9. "Enabling" 2WD-L transmission mode

[this chapter is still in the making - more changes and additions are planned to be written]

Jimny has part-time four wheel drive transmission system. That means that the engine nominally drives only the rear axle (rear wheel drive). Since only two wheels are driven, that is called "2WD" mode.

The driver can manually engage "4WD(-H)" mode. In that mode, the front axle and front wheels get connected to the transmission as well, and then all four wheels receive engine power.

However, because the transfer box contains no center differential, the front and rear propeller shaft always have to rotate at the same speed in 4WD mode. This in practice means that Jimny must not be used on non-slippery surfaces when in 4WD mode (except for very short distances and ONLY going dead straight). Otherwise, the transmission be severely damaged! If steering to left or right must be done while Jimny is in 4WD mode, the road surface must be very slippery for the transmission to be able to relieve the tension caused by the lack of center differential. Wet tarmac roads are typically not slippery enough for 4WD, nor are hard gravel and dirt roads, nor dry grass fields.

Now, Jimny also has low range gears, meaning that it can effectively halve all of its gears' speed while doubling the torque. That functionality is essential for any serious all terrain duty, and very helpful even on gravel roads of varying constitution.

However, Jimny's transmission controls (both older stick-style mechanically operated and newer push-button-style electrically operated) allow the low range to be engaged only if 4WD is already engaged. Therefore, Jimny allows only "4WD-L" mode to be used.

This means that low range mode is always severely constrained by the above mentioned disadvantages of ordinary (high range) 4WD mode.

On the other hand, in practice there can be several situations where "2WD-L" mode would be desired - using low range gears without 4WD mode. In that mode, steering would be safe to do on any kind of surface.

Typical situation is when driving on a dry, rough, twisty gravel or rocky road. On such roads, steering is applied a lot, the road surface is difficult so requires 1st low gear or 3rd low gear, but the road surface is not slippery. Using 2WD-L mode would be ideal.

Another useful situation for 2WD-L mode would be to tow a trailer some short twisty distance, or to make an easier start with a trailer when going uphill.

Also, parking in and out of difficult (sloped) parking positions would be much easier with 2WD-L mode.

So, how to "enable" 2WD-L mode?

Technically, 2WD-L mode can work in Jimny's transmission system. Simply don't connect the front propeller shaft to the transfer box, and don't engage the front wheel hubs. This can be done manually by removing the front propeller shaft and disabling the vacuum system for the front wheel hubs. However, 4WD mode would be permanently lost (until everything is returned back).

Suzuki could have simply made the 2WD-L mode possible by making another "program / position" its 4WD controller, where the controller would only operater the low range selector in the transfer box, and leave the front propeller shaft and the front wheel hubs disconnected. But they did not, either because of lack of thought or because some manager thought that adding one more transmission mode would confuse a typical user.

So, the question is how to add/enable the 2WD-L mode "systematically", to be selectable any time from the cabin and to be compatible with the 4WD controller and all the mechanicals.

The solution depends if the Jimny has older stick-style mechanically operated transfer case, or newer push-button-style electrically operated transfer case.

More on the specific solutions later on ...

10. Transmission breathers

Jimnys axles and transfer box have small caps which serve air breathers which allow air to come in if the oil inside cools (and contracts) rapidly (for example when the vehicle dips into deep mud or water). However, there is a risk of that mud or water coming inside through those breathers, fouling the oil and causing expensive damage.

Therefore, it is very advisable to install extended breathers at least on front and rear axles. The "extended breathers" are nothing more than rubber hoses! They are dead simple to install. Installing them on a transfer case is more complicated (the transfer case should be dismounted first), and there is a much lower risk of it getting water over it anyway.

To install extended axle breathers on the axles, just buy good quality rubber hose (approx 6-7 m of length) with internal diameter of 1/2", and a few good quality metal screw-tight straps for hoses. Remove factory breather caps from the axle differential housings and put on the rubber hoses, and tighten the metal straps on the connection point. Lay the hoses through the underbody, in the engine bay, up to the bonnet height, avoiding hot surfaces. You do not even strictly need a "T" hose connector for interconnecting the two axles, as each hose can go independently up to the top. Tie the hoses here and there with plastic strap ties, and leave enough extra slack hose near the axles, because the axles move up and down during usage.

During usage, check the hoses now and then in case that they are starting to come off at the axle connection point (you DO NOT want them to separate as that will leave a gaping hole for anything to enter the axles).

It is also advisable to put some thin meshy cover on the top of the hoses in the engine bay, to prevent ingress of dirt or bugs (but still allow air to pass through).

11. Fluids and filters

If you recently bought a second-hand Jimny and are not confident in its service history, change ALL fluids and filters.

That means oils in:

• engine,
• front axle,
• rear axle,
• gearbox,
• transfer box,
• power steering,
• brakes,
• air conditioning oil and coolant (if fitted),
• engine coolant.

Required oil specifications and quantities are written in the owner's manual.

Filters are:

• engine oil filter,
• engine air intake filter,
• cabin filter,
• fuel filter for DDiS (diesel) Jimnys.

12. Lifting the vehicle

A lot of people dream about lifting their 4WD vehicle, as they consider that to be an epitome of off-roading - a main beneficial mod for off road use.

However, lifts come with many disadvantages and costs. They might require extensive modifications of suspension, steering and driveline components. They will make a car more unstable on the road.

Also, the benefit of a lift highly depends on the extent (severity) of off road terrain. Jimny is already quite capable in its stock form, and slightly larger tyres might be all that is needed. It is advisable for the driver to first drive his vehicle a bit, and experience all of his intended off-roading situations before deciding if a lift would truly be required.

Therefore, if you do decide to lift the vehicle up, then it would be a good countermeasure to widen its stance (to stabilize it) by installing wheel spacers or using offset rims. For road use, it is not recommended to lift Jimny above 2" or use spacers thicker than 3 cm.

JimnyBits has a 1,5" lift kit which is supposed the be the most "sensible" option (least amount of vehicle modifications required to accomodate the lift), so consider that first.

A stock jimny with no lift nor spacers (apart from slightly larger tyres) can still get to most places where you intend to go, just with more skill or attempts applied (and that's the name of the game).

13. Deep mud and water terrain

Although Jimny can be used for deep wading or mud bogs if you install transmission breathers and the snorkel, bear in mind that Jimny has a weakly designed front wheel steering knuckle, which is prone to water/mud ingress, and that damages kingpin bearings, CVs, etc.

It is very hard to prevent water/mud ingress there (use of some hardcore sticky waterproof grease inside can help to deter water and mud, but that's it).

Therefore, it's best to avoid mud bogs and deep water.

If you want to get really filthy on a regular basis, use a Defender, Land Cruiser, Patrol, G-wagen or something else that was 5-10x more expensive than a Jimny when it was new. Or be ready to become a trained expert at working on Jimny's front wheel assembly.

14. Recovery points

If you intend to go off road, there is a good chance that you will get stuck no matter how equipped your vehicle is nor how "sensibly" you intend to venture. Therefore, you should invest in strong recovery points. If you don'n, and the factory recovery point breaks, you will have to use money as a recovery point, but it needs to be a thick stash of bills to endure the load!

Jimny's front tow point is weak, especially if the pulling direction is sideways. It can be VERY dangerous if the recovery point breaks off during pulling, as it becomes a lethal flying missile.

Therefore, it is important to have strong front and rear tow/recovery points, and it is best to have two front and two rear. Unfortunately, there are hardly any professionally manufactured aftermarket recovery points for Jimnys (and Suzuki does not make them). Your best bet is to weld on something of your own design (and your own trust).

When towing/pulling or being towed/pulled, always connect an "equalizer" tow strap to both the left and the right recovery point, as that will divide the load between the two recovery points. Connect the main snatch strap or tow strap to the equalizer strap, and the other vehicle to the main strap. If you use just one recovery point, you double the risk to rip off your recovery point, or bend the chassis arm if the lone recovery point is indeed so strong!

Using omega shackles rated at 3,25 T should be sufficient for Jimny, especially when the load is divided between two recovery points.

15. Front bumper issue

Jimnys have been in production since 1998, and there have been tree front bumper models on them - 1st gen. bumper (1998-2005), 2nd gen. bumper (2006-2012) and 3rd gen. bumper (2013-ongoing).

The 1st gen bumper is the smallest one (does not hang too low to the ground).

The 3rd gen. bumper also is not bad.

However, 2nd gen. bumper is overly large (hangs very low to the ground), and it significantly reduces the approach angle - the risk of it hitting the ground is quite higher than with other two bumper models.

Therefore, the 2nd gen front bumper is the most endangered point when off-roading, and it's easy to damage.

Also, 2nd gen. bumper reduces the space around the front wheels, limiting the size to which the wheels can be increased (by using larger tyres). With 2nd gen bumper, the usual limit is 205/75/R15 (and even that size sometimes makes a contact if the bumper is sagged), while with the 1st gen bumper even 215/75/R15 is not a problem.

For all the mentioned reasons, some people trim the 2nd gen. front bumper, but it tends to look ugly.

If you have a 2nd gen. front bumper and you find that it obstructs your offroading "potency", the best alternative is to buy a second-hand 1st gen. front bumper (1998-2005) from a scrap yard, paint it if needed, and install it instead of 2nd or 3rd gen. front bumper (the mounts should be almost 100% compatible - but I have not tried yet).

Another alternative is to buy an aftermarket heavy-duty metal "off roader" front bumper which can also be used for adding driving lights, winches, a statue from the front of Titanic, etc. But metal front bumpers might not be legal in certain regions. They also increase the weight of the front of the car, possibly sagging the front suspension.

16. Mud flaps

Consider installing mud flaps, especially if you intend to use wheel spacers or offset wheels - you will spend less money on washing the car (or maybe you like to be dirty).

Just bear in mind that you will have to trim front mud flaps' plastic spacers (between the mud flap and the wheel arch) for 205/75/15 wheels (nothing scary nor complicated). However, front mud flaps will probably have to be removed if you want to use tyre sizes 195/80/R15 or 215/75/R15 (or larger) together with wheel spacers or offset wheels.

Install genuine mud flaps.

If you install rear mud flaps, it is suggested to drill two holes (fi=30 mm) in the bottom of the rear bumper, behind each mud flap. That will enable the mud, which regularly accumulates in the rear bumper behind the mud flaps, to drain off. Otherwise, it is almost impossible to flush out.

17. Rear wheel inner arch mounts

In the rear wheel arches, there are metal lips which were meant to be mounts for the inner plastic wheel arch covers. However, as far as I know, Suzuki has never produced those inner plastic wheel arch covers. Therefore, these inner metal lips just accumulate mud and grit above them, which is quite difficult to flush out. Eventually the area will rust.

It is recommended that you either grind these inner metal lips off, or fill the space above them with some filler mass (thick bitumen, silicone, whatever). That will prevent the mud and grit from accumulating in your wheel arches.

18. Side window wind deflectors

Consider installing wind deflectors on the side windows. Very handy items! They reduce wind noise when cruising, and enable you to open the windows a bit even when it is raining.

Original ones are the best fit (and it is a tight fit indeed). Clearances on the top of the doors are really tight for the moving side windows, and you do not want to harden the life of your electric window motors more than you need.

19. Differential housings

Jimny is one of are vehicles today which has both front and rear solid axles. It is one of the last Mohicans.

Therefore, it deserves some war paint.

Paint your front and rear differential housings in a striking color (yellow, red, green). It will make you smile more often. Beware: kids on the street might think that a ball got stuck under the car.

20. Headlamp light bulbs

Jimnys use H4 light bulbs in headlamps. The ordinary light bulbs can be replaced with something stronger to give better illumination.

There are several solutions "on steroids", like Xenon(alike) lamps, various HiD technologies, LEDs, etc. However, most of them are illegal for on-road use in most developed regions of the world, unless the vehicle goes through some recertification process. Therefore, none of those "super solutions" will be covered here.

One solution which (should be) legal is the use of better engineered standard halogen technology bulbs.

Two popular bulb products of that type are Osram Night Breaker (much improved illumination, much reduced life expectancy) and Osram Silverstar 2 (moderately improved illumination, slightly reduced life expectancy).

There are other such products from other manufacturers of course. The important thing is that you look for a standard halogen technology bulb, but with improved illumination. Beware that illumination strength and life expectancy are usually in reverse proportion.

21. Installing additional driving lights

Installing some additional driving lights (either for forward or reverse driving) is on most people's wish list.

Beware that installing additional external lights on a vehicle might be illegal in some regions of the world, or may require that the vehicle goes through some recertification process.

Two possible mounting points for the driving lights are either somewhere on the roof, or somewhere on/around front or rear bumpers.

Since most Jimnys have factory longitudinal roof rails, the best way to mount the lights on the roof is to install transverse roof rail(s) and then mount the lights on transverse roof rail(s). The wiring then must be put through the cabin up to the roof. The disadvantage of roof mounted lights is that they increase air resistance during high speed driving, and may also induce significant wind noise. Also, the need to carry something else on the roof might be hindered by the presence of the lights on the roof.

If you want to mount the driving lights on/near the bumpers, you have a problem that Jimny has modern soft plastic bumpers. They are inadequate to be mounting points for the headlights.

In case of the rear bumper, (very small) driving lights can be installed only in the bumper itself (by cutting a hole in it somewhere near the rear lights). Mounting anything on the bumper is out of the question, unless you don't plan to ever open the rear door.

In case of the front bumper, it is not advisable to mount anything in the bumper holes where there are factory ventilation grilles (except for very small lights), because that might severely restrict the air flow towards the engine heat radiator.

One pretty solution is to install a metal "bull bar" ("nudge bar") in front of the front bumper, and then mount the driving lights on the bar. However, bull bars are illegal in certain world regions. Also, bull bars significantly reduce vehicle's ground clearance (specifically: approach angle).

One simple solution (in theory) is to simply drill two holes on the top of the bumper (in front of the hood) and mount the driving lights on the bumper itself. However, as the bumper is made of thin plastic, it vibrates and wobbles during driving, and so will the lights that it would carry. Unless you fancy looking at the "dancing lights" in front of your vehicle while driving, you might quickly get sick of that annoyance.

The vibration issue can be remedied by one of two methods:

1. Reinforce the top of the bumper (from the inside) so that it becomes thicker / stronger / stiffer and does not vibrate and wobble. This is typically done by applying one or two layes of special plastic net soaked into thick epoxy resin (that's what vehicle bodywork restorers do when they fix damaged plastic vehicle panels). However, this solution might not entirely fix the vibration issue, depending on the weight of the driving lamps.
2. Fabricate and install / weld your own metal mounts behind the front bumper, which would hold onto the chassis. The mounts should end right below the top of the bumper. Then drill two holes in the top of the bumper just above the mounts. This will enable the driving lamps to be screwed into the mounts, and the bumper will have no weight bearing function whatsoever. This is the best solution, and completely eliminates the vibration / wobble issue. However, any future removal of the front bumper requires prior removal of the driving lamps.

22. Sound system (player)

Factory radio-CD player in Jimny can only play audio CDs, and is quite fussy about which ones it accepts. There is a solution without replacing the factory music player.

Installing this simple Chinese-made add-on enables MP3 playback from an SD card, USB stick etc.: [4]

It works quite well and is intuitive. You can upgrade it with Bluetooth handsfree if you want.

23. Sound system (speakers)

Jimny has only two weak and dull front speakers. However, it has pre-machined space for a pair of rear speakers as well, as well as part of the wiring for them. If you replace the front speakers with something good, and install a pair of good rear speakers, you will get a significantly improved sound (nothing "boombastic", just solid and proper).

Links: [5] [6]

24. Increasing cargo space

If you need more cargo space, buy roof racks and a roof box. Bosanek used Thule "100" ("S") and "200" ("M") size roof boxes on his Jimny.

Thule boxes have several models, but their sizing names are the same across the model range. For example, Ocean 100, Pacific 100, Touring 100, Touring S, Motion S, etc. they are all almost the same size. Sizes 100 and 200 fit great. Size 780 also fits, but looks just a bit bulky. Anything larger than that looks like a boat on the roof.

You can regularly go off road with the roof box on, just bear in mind that your center of gravity is higher with the roof box on (especially with cargo in it). It is important that the box is of high quality so that it can withstand vibration abuse when driving on gravel and off road.