Damage from running smaller spare?

[V8 Middy]

I'm running 35in tyres but I can only fit a 33in spare on the back at the moment. I'm guessing its not great for the car to run uneven tyres but how far can you go before it causes real problems?

Some people have said not to run it on the back as it will screw the diff but then plenty of modern cars have a smaller diameter spare. Obviously running in 4wd would be asking for trouble!!!

Thanks

[Chucky]

If you are on the soft stuff I dont hink it wont really be a issue.
On the road thou I would swap it with a front tyre and unlock the hubs.
On most road cars that have smaller spares they are speed limited when using the spare. Personally I wouldn't be too bothered about it, but would also get teh prignal fix asap.

[GQ Bear]

I've had to do it a couple of times unfortunately. I've encountered no problems. Longest stretch was Toolangi to Moorabbin (about 150kms).

Run em on the front in 2wd with hubs unlocked. I put about 50psi in spare Sumitomo 33x12.5R15 and about 18psi in Simex 35x11.5R15. Feels a bit strange, but take it easy and no probs.

[TEAMRPM]

I've had to do it a couple of times unfortunately. I've encountered no problems. Longest stretch was Toolangi to Moorabbin (about 150kms).

Run em on the front in 2wd with hubs unlocked. I put about 50psi in spare Sumitomo 33x12.5R15 and about 18psi in Simex 35x11.5R15. Feels a bit strange, but take it easy and no probs.

wouldn't be a problem providing you dont use 4wd, at all. if you have a lsd rear diff i would change the smaller 33" tyre to the front and leave it at that. it will destroy your lsd if you have one. it will consistently be slipping

[nicbeer]

What about a autolocker? would same principle apply. i will be running welded rear and locker in front.

[Dee]

i think if you tried to run it on the rear with a locker you would break an axle or something in no time.

Just swap a fullsize from the front to the rear, and put the smaller one on the front, with hubs unlocked in two wheel drive only.

Dont put 2 different sizes on the rear, or lock hubs with 2 different sizes on the front!!!

[LincolnBlack]

another point to raise is full-time 4WDs. These bad-boys don't have any hubs to lock in or out. Even though it designed to do it (ie differentiate )I wouldn't think a differential, even unlocked, would cope well for an extended period of time no matter which way you put the tyres. In which case

[frp88]

I ran a pissy little 28 inch that came with the car for weeks on black stuff only no drama it didn't pull or drive to side. But it was on the front saying that if you have an open rear then it shouldn't be a drama.

[frp88]

I ran a pissy little 28 inch that came with the car for weeks on black stuff only no drama it didn't pull or drive to side. But it was on the front saying that if you have an open rear then it shouldn't be a drama.

[Gwagensteve]

I've never had a full sized spare on the G wagen, and don't have hubs either (but I am not constant 4WD - kooky Germans)

I have had to run a missmatched spare a few times, and it hasn't been a problem.

Don't run in 4WD on hard surfaces (never really a good idea anyway)
Run the smaller tyre on the front.
Won't be a problem to get you home.

Wouldn't run it on the rear of a car with a detroit for any distance at all on tarmac.

33-35" is farily insignificant and I don't really think it would even put that much more heat into the diff of an open diffed car - think about the constant variations when driving on a windy road.

[j-top paj]

On the road thou I would swap it with a front tyre and unlock the hubs.