Different Size Tyres

Probably no worse than having 4 tyres that are just about worn out and then having one pop and you put on the full tread spare that has been hanging on the back door for 3 years because you never got around to doing a rotation. Plenty of people do that!

Muddy

Richard

I agree with Muddy. You have a difference of around 26 mm in diameter which is about what you would have with a combination of a new and a well worn tyre. If the car was pushed to the limit on a sealed road by a professional driver, then a few deficiencies in handling and breaking would surface but you are not going to notice anything while bouncing quietly along an outback track.

It will cause the idler gears in the diff to turn over a little more but it would have to be left there permanently for a long time to have any adverse effects.

Make sure though that you have the equipment and knowledge to repair punctures from both inside and outside tyres. Two spares are handy but plenty of people have run over a stake or sharp rock and punctured a front and rear tyre at the same time. If that happens you are still without a spare and one more puncture could really upset your day if you can't fix it.

Brian

Hi,
You have confirmed what I had hoped.

I am thinking of going from a 265/65/r17 H/T to a 265/70/17 ATR (LT construction) but did not want to have to buy an extra tyre (for second spare) given I have 5 spare tyres (still in good condition).

Along with tyres I am chasing down equipment to do as you mentioned. I already have a good plug kit and will do some trials before hitting the road,

Many thanks,
Rich

"I already have a good plug kit and will do some trials before hitting the road,"

Rich

Whatever you do, don't make the mistake of thinking a plug will fix everything. They certainly have their place and will get you out of trouble more often than not but after you have tried multiple plugs in a large hole and it is still leaking, that is no time to find that there are other ways to do it and you don't have the equipment.

Have a look at the puncture repair equipment on the Rema Tip Top web site. That will give you a good idea of what is available. I addition to a variety of plugs that are applied from both inside and outside, there are also multiple size reinforced patches available. You should also carry a tube.

See if you can try before you buy when it comes to bead breakers. There are a number of different types available and some require a fair amount of physical strength to use them.

Changing and repairing tyres is a bit like fitting snow chains. You don't make your first attempt to fit them in knee deep snow, you practice at home first and it is wise to do the same with tyres.

Brian

Hi Rich

After fitting a different size tyre adjust its pressure such that the rim is about the same distance from the road as the other tyres.

Don't travel to fast and you'll be alright for a while if also using common sense.

I often carry 255/85 as a spare and run smaller 235/85 when around town.
Not a real issue , espically in my case where the Patrol can be 2wd and I have the LSD removed.