Largest tyre size that Jimny drivetrain can handle

Hi everyone. Just gathering some info for potential new project ideas and a Jimny based build is one of them because it's a very lightweight, affordable, up-to-date, and respected car.

What's the largest tyre size that the Jimny drivetrain can take under abusive offroad conditions like challenge events? Ie at what tyre size will I start facing broken axles, propshafts, anything like that? Forget the tyres rubbing on the body/chassis, I can solve those limits. And same for the engine power, I can solve that.

Also how similar is the Jimny to the earlier SJ? Does it still have an intermediate propshaft between the gearbox and tbox? Is there still a gear ratio step down in high ratio in the tbox or is it 1:1?

Thanks for any help!

29 inch tyre is about the biggest you can go without mods but you can break the shafts and cvs on standard tyres . Depends on your driving style . If your going to do challenge style events you will have a big list of things youll need . 3-4 inch lift , uprated radius arms ,hd pahnard rods , 31 inch tyres , if you want to run those size tyres then youll need a rocklobster transfer box , suzuki sj props , uprated shafts and cvs . Manual locking hubs . Or even better some toyota 70 axles . Standard transfer box is useless with big tyres .dont get me wrong the jimnys are grate in standard form . But to do challenge events they need some mods

Transfer box is the first thing to swap out for a rock lobster really, standard one doesn't have a low enough low range, as soon as you put larger tyres on it will struggle to accelerate as would any car and a lobster box fixes both of these problems, plus a standard transfer case is chain driven and not the best in use , easy to stretch the chain under load leaving you needing a SH transfer box as the chains are £300 and supposedly best fitted with new gears at the same time. I like 750x16 tyres which are tall at nearly 32" but not very wide - wide tyres don't dig in so well on such a light car. To fit 750x16's you will need a 5:1 rock lobster transfer case as oppose to the more common 4:1.

Gary

Flameboi201 wrote: 29 inch tyre is about the biggest you can go without mods but you can break the shafts and cvs on standard tyres . Depends on your driving style . If your going to do challenge style events you will have a big list of things youll need . 3-4 inch lift , uprated radius arms ,hd pahnard rods , 31 inch tyres , if you want to run those size tyres then youll need a rocklobster transfer box , suzuki sj props , uprated shafts and cvs . Manual locking hubs . Or even better some toyota 70 axles . Standard transfer box is useless with big tyres .dont get me wrong the jimnys are grate in standard form . But to do challenge events they need some mods

Easy on those mods

We're doing winch challenge events, and doing pretty well on a 2" lift with only 235/75/15 tyres. Also on standard radius arms with C/C bushes. The thing with bigger tyres is that they require more power to spin than smaller tyres. So if we wanted to go for 31" tyres, we simple wouldn't have enough power.

But agreed, uprated axles is a must. But I would go for uprated internals, for 2 reasons. The toyota axles are both heavier and wider.

Also, instead of just wanting the biggest lift posssible. Get a lift that suits the event and tyres, a 2" lift is more than enough. And buy good quality shocks. I'm considering saving up for som Fox 2.0 remote reservoir. They're a bit expensive. But a far better ride

Yes I have a 3" lift but it's sagged after being fitted for over 10 years ! Heavy bumper and winch don't help. I've trimmed the inner arches where they meet the floor pan and also the body mount under the headlight , currently running 31x10.5x15's

Gary

Thanks for all the info. Are there examples of Jimny builds, or Jimny based rigs, which have been built or heavily modified and are able to compete in events on par with challenge events? I mean something on the lines of what Rockwatt has done with his SJ "Zero"? Or more extreme even.

With gear ratio corrections, I do have a Rocklobster acquired from a previous project. Hopefully there's aftermarket crown wheel & pinions or tbox gears available to make further gear ratio mods if necessary.

Are Jimny's more prone to failure than the previous SJ's then? Ie they didn't have chain drive in the tbox and Flameboi said that SJ propos are better.