Off-road wheels & tyres - quick sanity check

Down at my local club my Jimny does pretty well, but it soon runs out of ground clearance (where another lifted Jimny easily gets through) and my Maxxis Worm Drives can loose grip on the muddy/sand/clay/soil surface.

Looking at all of the vehicles that do well, they all run Insa Turbo Special Track, so I have decided to go for a set of Special Tracks on spare wheels (just for off-road and travel to the site), but the question is which size?

I now have a 2" lift (to help with ground clearance) and allow taller tyres, but want to avoid going too wide (tall/skinny tyres are the way to go I think), so the options are:

Special Track
195/80 r15 - These will fit my spare set of 15" alloys, but they are 0.4" smaller on diameter than my Maxxis, that's only about 5mm lower ride height.  They will of course fit and they are a nice tall tyre.

205/70 r15 - These will fit my spare set of 15" alloys, but they are 1.4" smaller on diameter than my Maxxis, that's about 19mm lower ride height, so not attractive from a ground clearance point of view.

205/80 r16 - These will require new wheels, they are 1.2" bigger on diameter than my Maxxis, that's about 15mm higher ride height.  These fit the requirements for a tall narrow tyre.  I have checked clearance using my Maxxis as a guide and think they will fit without any trimming, or perhaps minimal trimming?

All the Special Track sizes after these are quite wide, 235 is the next nearest, they will require new wheels in any size as my alloys are 15 x 5.5".

There is also Insa Turbo K2, a slightly less aggressive tyre (205/80 r16), but I don't know anyone who runs these and there doesn't seem to be too many reviews.  They might be slightly better on the road, but that's not a high priority for me.

Wheels
If I go for 16" tyres I need some new wheels, Jimnybits sell steel wheels in 16" in 4 offsets, although for me I think only two are relevant, either ET 0 or ET +10.  The wheels are 7" wide so 205/80 fits on them but the wheel rims will stick out further 14mm on one side and 24mm on the other from standard 5.5" wheels.

I have checked clearance behind each wheel and there doesn't seem to be an issue so I think I would prefer the wheel rims to stick out from the vehicle less so would go for ET +10, does that make sense?

Balancing
I am going to go for balance beads rather than weights.

TPMS
Originally I was just going to ignore the TPMS warning or stick a bit of tape over it, but I think I will buy an Iron Gates emulator to get rid of the bleep and dashboard warning.

What do you think, before I press the buy now button?

Robin



 

I have no direct experience to offer, just wanted to remind that the kei Jimny runs 16-inch wheels as standard. So perhaps a Japanese Jimny forum would have some useful info re offsets and tyre sizing, as you are collecting data.

Remould tyres often come up way way bigger than the stated size. Might be worth visiting your local tyre place and ask them to line the tyres up, so you can see the difference.

I ran 235/75R15's on my 4th Gen, this tyre should be the same height as a 205 x 16 in theory. I have 205's on the Freelander, but they are just an AT. You'd really want to see how big the remould was.

I say this, as a lift does't really allow bigger tyres, not unless you have stopped the suspension compressing, but that would be bad generally as it would mean less suspension travel.

I had an after market front bumper on my Jimny, so had no issues with clearance, but it wouldn't surprise if the bigger sizes might see some rubbing on a stock bumper.

Do you plan to re-gear at all? For me the Jimny was always way too fast in low 1st. Bigger tyres sadly do not help this.

From a tyre perspective the 205 x 16 would be the best, but I suspect the 195/80R15 might be taller than you think it will and will be a direct swap for less money.

While the 205 x 16 will go on a 7" wide rim, it would be more ideally suited to a 5-6" wide rim. But I could not find any steel rims this narrow for the Jimny, only expensive alloys...

Off set wise. I wouldn't go narrower (+ET) than the regular car. The Kei version has a narrow offset to keeps the wheel inbound more. But a tall tyre is then more likely to foul the radius arm or inner wings. You may also reduce your turning circle.

For trialling we tend to run a wider offset at the front, and a narrow off set at the back. As this maximises your turning circle and make it harder to drive over a cane with your real wheel when turning hard.

But you don't want outside the arches at the front.

I would say balance weights would be fine, I wouldn't worry with beads. While technically they can work the physics behind it means they don't work anywhere near as well as you may think they should.

Here is a 205 x 16 compared to the 215/75R15's. The 205 is not mounted and has no weight on it, but they look surprisingly a lot taller than the stats may suggest. And these aren't remoulds, the Insa Turbo 205's are likely quite a bit wider and probably a bit taller.

Thanks for reminded me that the Kei was supplied with 16” wheels, but I understand that the Kei doesn’t have flared wheel arches so uses a higher ET +22 with 195/80 r16 to keep the wheels within the body work.

If the Kei can get away with ET +22 and 195/80 r16 a UK Jimny should easily be able to cope with ET +10 205/80 r16 as far as width goes, but I will double check tomorrow.

You have of course hit the nail on the head and exactly what I am concerned about, remolds, especially ones with a very chunk tread are actually substantially bigger than the size quoted.

I did email the supplier, but I suspect they quoted the nominal size as it was exactly the same as ‘TyreSize.com’ gives.

I did post a question on an Aus forum and someone replied saying a small amount of trimming would be required to the plastic at the front, otherwise they would be fine. Unfortunately my local tyre place doesn’t have these in stock.

I have budgeted for new wheels, that cost doesn’t bother me, but I would really like to find out if 16” Special Track will fit before I hit the buy now button.

I suppose the ideal is find someone with 205/80r16 who can measure the actual diameter or someone with 195/80/r15 and I can make an educated guess.

I take your point about gearing, mostly I use Low range 1st gear, but there seems to be plenty in reserve and think it would be OK, it’s only 5% more diameter (providing the size is reliable).

Thanks for all of your input, still more to think about/check.

Robin

So balance beads only work if the tyre spins fast enough, which is kind of what you would guess, at very slow speed gravity would just cause them to sink to the bottom.

However, moving faster is exactly when you want them to work, at slow speed, especially off-road you wouldn’t notice any difference if the tyre was in balance or not.

The problem with chunky/aggressive tyres is that they can be very difficult to balance with weights, so if you can’t achieve balance with weights then you can with balance beads.