Thread: Largest tyre sizes on a standard ratio driveline?

Originally Posted by AndrewGJones

First bit is wrong, the last bit is right. Larger tyres speeds you up for any given revs, but off the line you are working the clutch/ drive line harder to get moving.

Yes, speed was the incorrect term used by me, I should have said reduced acceleration. I was attempting to make reference to the effect felt by the driver due to the larger tyres - the vehicle feels slower as the acceleration is reduced and the engine has to be worked harder to get up to the speed.

Originally Posted by twr7cx

+6mm will push them out by 51mm each side which is beyond the largest increase allowed.

I take it you're talking legal increase??

Sorry, I don't understand your argument, unless Tassie has far different rules on this.

Going to 33's is beyond the largest increase allowed too isn't it??

My point is, if either option (larger tyres or wheel track) is going beyond legal increase, then both being beyond legal increase is the same thing. If you're looking to keep it legal, then the point of going to 33's becomes invalid anyway.

Originally Posted by brenno

I take it you're talking legal increase??

Sorry, I don't understand your argument, unless Tassie has far different rules on this.

Going to 33's is beyond the largest increase allowed too isn't it??

My point is, if either option (larger tyres or wheel track) is going beyond legal increase, then both being beyond legal increase is the same thing. If you're looking to keep it legal, then the point of going to 33's becomes invalid anyway.

Yes, 33" will require an engineer approval and speaking to them (as I've detailed in other threads), because of some similarities between the Defender and Discovery 2 axel and the Defender being able to run up to 33.7" without engineer certificate, they are willing to proceed with approval.

As for increasing the offset further they were not willing to consider it.

Originally Posted by twr7cx

Yes, 33" will require an engineer approval and speaking to them (as I've detailed in other threads), because of some similarities between the Defender and Discovery 2 axel and the Defender being able to run up to 33.7" without engineer certificate, they are willing to proceed with approval.

As for increasing the offset further they were not willing to consider it.

Ah ok... I wasn't aware you were getting it engineered.

Good luck with it then. As I said, I'm running 33's with 2 inch lift on standard offset alloys, and have no rubbing or scrubbing.

That's good to know Brenno, I was a bit worried about rubbing with the 285's. I'm only running a 2" lift at the moment but that should be irrelevent as the compressed height will be the same as yours unless you have extended bump stops.
My Zu rims arrived today (well 3 out of 5 arrived, hoping the rest turn up tomorrow) can't wait to get the 33's fitted.

I was looking at going up to 285 75 16 or 255 85 16 from 32's,for off roading. Has anyone used 33's with a standard ratio D2 TD5 Manual. I want to know if it's to much for the manuals drivability

Originally Posted by Landover

I was looking at going up to 285 75 16 or 255 85 16 from 32's,for off roading. Has anyone used 33's with a standard ratio D2 TD5 Manual. I want to know if it's to much for the manuals drivability

Not having a manual, but having done a lot of difficult driving with many that do have manuals, they are all good drivers but the manuals really don't do crawling or slow controlled work very well and the reduction in gearing makes this pretty untidy at times,especially when you are at that point where you really want things to be going well. My opinion is that in a manual, if you're putting larger tyres on, and you do difficult technical 4wding, ie not just tracks, then you really need to look at 30% transfer gears at least.

Why not just change the diff ratios?