Thread: any dramas using a different sized spare?

Originally Posted by CraigE

Best to change both tyres (front or rear) if you are in a jam and need to use a different spare. My trailer tyres on 16" Rangie wheels are 225/75R16 and on the Fender 235/80R16 and while the wheels will fit and are similar the over all rolling diameter is different. So if I had a drama on the Fender and used the spare and had that fail I would take 2 wheels off the trailer (trailer spare and one of the wheel on the trailer) say it was rear LH and replace both rear wheels and put the odd ones on the trailer as it will not hurt the trailer. Safest way with minimal impact on your diffs and trans. Should be OK running different sizes front and rear for a short time but never one side only.
Cheers
Craig

I would dissagree with this. To run like that you will be making your center diff work hard. If you only run one different diameter wheel both the rear diff & center diff will share the difference in rotation speeds.
Al

I always thought space saver wheels and tyres were to same rolling diameter - just a lot narrower.

Garry

How many times do you think mechanics see broken vehicles because of things like this?.Their your vehicles and it's your money.I suppose you can aways jump on the ''LR diffs are weak'' arguement after you chew one up. Pat

AFAIR Land Rover recommend That the diameter difference between tyres should be a Maximum of 10% for emergency use. 235.85x16 is 11-12% more than 225.75x16 so you shouldn't do it.
Space savers are NOT the same diameter as the normal tyre , they are much smaller. The one in SWMBO Mazda 121 said not over 80KMH and 200Km? AFAIR.
I agree that one tyre would be better, as the rotational difference would be shared between 2 diffs.
I had the same issue as I had/have 245.75x16 on the car and 205.80.x16 on the trailer, but the rotational difference is only 6% without taking inflation into account. Luckily have never had to do it.
Regards Philip A

Originally Posted by jimbo110

Many cars have space saver spare wheels which are a different diameter and width than the normal road wheels. An open diff would hardly know the difference and would be fine, a locker/LSD would be a different story. If you have standard diffs and dont engage the center diff lock on hard ground you will be fine.

I thought that's what I said.

That's why you have the trailer tyres and rims,
the same as your Vehicle.

Originally Posted by numpty

I thought that's what I said.

So did I, I was agreeing with you

I just wanted to add the lockers bit.

A lot of good advice given here, and I agree on highway would not hurt over a small distance 100 ks or so but If you were involved in any sort of accident you would / could have a big problem with your insurance company. My brother years ago had two different size tyres fitted on the rear of a ute lost control in the wet in a bend ute was a write off and the insurance coy wrote him off said the car was unroad worthy.

Hodgo