Introduction:

One of common questions about improving vehicle's all-terrain performance and endurance is "what is the most effective modification to apply to my vehicle?". Well, using proper tyres, and using them properly, is arguably the most effective vehicle "mod" for all-terrain use.

Notice: "Most effective" can generally mean in the context of cost, performance, simplicity or endurance. Using proper tyres properly is can be the most effective "mod" in all of those ways!

This document includes on the following topics: 1. Choosing a proper tyre type for the desired usage; 2. Choosing a tyre size; 3. List of various tyre models with remarks; 4. Best practices on tyre usage (wheel rotation, wheel balancing, air pressures, rim and tyre repairs); 5. Special situations and combinations;

General remarks

First of all, some basic remarks about using tyres on four wheel drive vehicles:

1. Jimny is a part-time 4WD vehicle, and an inherent requirement of that transmission design means that all it has to use all four tyres of the same profile (size). Furthermore, all four tyres should be the same model and have a very similar tread depth (even small differences between rotational friction and wheel circumference among wheels can damage the transmission in the long term). This limits the combinations when choosing (buying) tyres. Notice: Even full-time 4WD vehicles should use all four same tyres because, when their central differential gets locked in all-terrain use, they behave the same as part-time 4WD vehicles.

2. Frequent checking (and adjusting) of air pressures is much more important for all-terrain use than on ordinary on-road use, because pressures significantly affect traction as well as the risk of tyre damage.

3. Wheel (dis)balancing is a much more prominent issue for all-terrain use, especially for Jimnys as they are notorius for developing a "death wobble" issue. It is a genetic trait derived from their short wheelbase and solid front axle suspension design.

4. For all-terrain use, higher profile tyres are always preferred against lower profile tyres. Reasons: higher profile tyres cushion the ride better on all-terrain both for the vehicle and for the passengers, they decrease the chance of rim damage, and they allow better air pressure management. Their only disadvantage is worse performance when the vehicle corners fast in a bend, but it is unsensible anyway to do so in a high, narrow, wobbly, jumpy, twitchy vehicle. Therefore, putting oversized rims with thin tyres on a 4WD vehicle is like putting ballet shoes on a village farmer.

Choosing a proper tyre type for the desired usage

Tyre designs for passenger and light truck vehicles can be (among other ways) designed and built for regular "on road" use (the vast majority of tyre models) or (to an certain extent) for all-terrain use.

The difference between those two design approaches is not just in tread pattern (traction capability). Another equally important aspect is tyre's robustness (resistance to various types of trauma), which is generally given dedicated design attention (based on tyre's exploitation expectancy). For ordinary road tyres, robustness is barely considered. Also, tyre's adaptability to different weather conditions is also sometimes given more design thought.

There is no official standard to differentiate various kinds of all-terrain tyre designs.

There are three "industry categories" of all terrain tyre designs, based on loose practical usage classifications (from "worse" to "best"): 1. HT - "Highway Terrain" 2. AT - "All Terrain" 3. MT - "Mud Terrain" (also called "Maximum Traction")

Tyre manufacturers usually use this classification to position their all-terrain tyre models in their marketing catalogue.

HT tyres generally have the best on-road performance and worst off-road performance of all three categories, while MT tyres generally have the opposite performance characteristics. AT tyres are generally in the middle - being good but not great for both.

Highway terrain tyres are generally meant to be used predominantly on road, with only slight light off road excursions (possibly rougher gravel, some grasslands, etc.). Their overall tread design is generally quite similar to ordinary road tyres. That means that they generally have equally proficient on-road performance even for sharp or very fast driving (and similar fuel economy), but almost equally bad all-terrain performance. However, having the "terrain" part in their name, HT tyres should be slightly more robust than ordinary road tyres. Conclusion - for (almost) always on-road driven all terrain vehicles, HT tyres can be an optimal choice if the vehicles are driven sharply or at high speeds. They are always recommended over ordinary on-road tyres for two reasons - they should be more robust and they at least formally "suit" the all-terrain image of the host vehicle. However, if all terrain driving is even occasionally performed, AT tyres are definitely a better choice.

All terrain tyres are generally meant to be used in mixed on-road and all terrain conditions (anywhere between 30% and 70% of time for either). They usually have significantly rougher (and a bit deeper) tread design compared to HT and ordinary road tyres. They are a performance compromise which is usually hard to achieve. They are generally good on-road except for sharp or very fast driving, and generally good off-road except for boggy and/or harsh conditions (deep mud, deep snow, sharp rocks, river crossings ...). They are usually significantly more robust than ordinary road tyres. They should slightly impact fuel economy. They can be a challenge to balance properly. Conclusion - for all-terrain vehicles which are used for everything - commuting, intercity travel, and various all terrain conditions, AT tyres are the solution. They should not present a jeopardy on the road, and they should be a trusted companion off the road, in the sense of traction and in the sense of reliability.

Mud terrain tyres are generally meant to be used predominantly off road, with only slight easy-going on-road excursions. They usually have very deep and striking ("tractor looking") tread (and sidewall) appearance, and very high robustness capability through various reinforcements. They excel in boggy and/or harsh conditions (deep mud, deep snow, sharp rocks, tree roots, river crossings, etc.) and offer the best protection against punctures and chipping. However, they are generally noisy on the road and present a real jeopardy if not driven carefully on a wet road and especially on packed snow or ice. Also, they usually significantly affect fuel economy. Due to their coarse construction, they can be very hard or impossible to balance properly. Conclusion - for all-terrain vehicles which rarely touch the asphalt and are used on tough terrain, MT tyres should be the weapon of choice. However, they can be a jeopardy on regular road surfaces and they wear out faster on road. Also, if not balanced entirely, they will cause issues on road.