Running 2 different tyre sizes

[LeeThr]

Just a quick question for all the legal boffins really. But as far as I understood I could run two different tyres sizes as long as each axel was identical. Is this true?

Whilst getting a tyre changed today the guy in the tyre place was going on at me for having a different size on the back to the front and that it would fail MOT like that. Is this true?

For reference the front is running 195/50/15 and the back is running 195/55/15 both matching on each side.

[Dodsy]

All TVR chimaeras run different sizes front and rear - Hes just trying to sell you 2 more tyres.

[Six Fiend]

Tyre fitter speak with forked tongue

[simoid]

As do the latest MR-2s IIRC: 15s and 16s.

[busta]

Nothing illegal about it.

[Snowboy]

Yep. You’re fine.

You can’t mix them on axles.
You can’t mix radial and crossply.

You might find a different size tyre to OEM makes the speedo read a little off.

You probably shouldn’t do it a 4x4 without a clever diff as it’ll probably bugger something up.

[Captain Muppet]

Does the car have ABS? If so the wheel speed sensors are going to think the rear wheels are turning 3% slower than the fronts, which might make a difference to the threshold of ABS. Or something.

I've got 195/50R15 on the front and 195/55R14 on the back of my MX5 this week. It's passed MOTs like that too. though frankly I have no reason to run the car like that other than being too cheap and too lazy to sort out a set of matching sized wheels and tyres from the heap in the shed.

[mercfunder]

Tyre fitter is talking out of his aris.

[LeeThr]

It's only on a 206 1.4 so nothing clever that requires absolutly everything to be prestine. He's probably just not happy that the last few times ive been in it's allways to get my own tyres fitted rather than buying theres. The front are running identical toyo proxes T1R both fitted brand new at the same time matching size. The back is running the same size on both sides but just running budget tyres.

I will get some more proxes for the rear soon though. This is just a stop gap whilst moneys a bit tight and to keep things legal.