Different size tyres on front and rear

I've run mush different tyre sizes than that between front and rear. "affect how the car handles" is an interesting one, the car will handle differently with a full tank of fuel to an empty one...

Whether it noticeably adversely affects is another Q.

I would have thought you would increase the tendency to understeer a little doing that, in theory, but there's more to that one than just size. Tread pattern, compound, etc. etc.

If it seems to drive OK, then it drives OK. I'd have said the difference either way will be minimal?

I've got 215/55 fronts and 265/75 rears on the camaro. I'm pretty sure 10mm difference in diameter won't be noticeable in any way. If you notice a difference it's beacuse the new tyres are of another brand, with different sidewall strenght, compound und so weiter.

I don't see how you can say that without knowing what car they're being fitted to. If I had to guess I'd be expecting it to be a FWD hatch, in which case I'd personally rather run the wider tyres on the front, as the weight distribution is likely front bias, and the brakes are likely overly front biased too, to prevent the rear locking in the dry.

Although that said, in this particular instance, it's such as small difference that like others have said, you'll notice more difference from the brand than the size, so I really wouldn't worry about it.

What would be worth bearing in mind is that if she gets a puncture on one of the now different sized tyres, then putting on her spare will give her miss-matching tyres sizes on that axle, which is illegal.

True, but I bet it's also got some sort of sticker on it with a maximum speed and distance on it. If you've just got miss-matched full sized wheels on there then they might not be so friendly about it.

To be honest you'd likely be fine using it like you would a space saver, but I was more thinking that with full sized spares a lot of people seem to slap the spare on then just leave it on there, making the wheel they took off the new spare.

My 106 van has 145/70/13s front 165/70/13s rear guessing they didnt have the right size in stock, not the fact that 145s were cheaper than the 165s.

Mind the MR2 runs 205/50/16s front 225/50/16s rear and its much better for it

oh yes.

IIRC its in The Road Vehicles (Construction and Use) Regulations 1986

I'm sure I've heard of production cars with wider front than rear tyres. Some mad FWD performance thing. Not necessarily one sold in the UK though not that this helps LOL.

I wonder if westy180 is thinking of the business about crossply on the front, radial on the rear and not the other way around. There was a story you could put the crossply on the back if they were over a certain size (with many old rods back in the day running big bias belt Grabbers on the back and 135 radials on the front) but I think this was also an urban myth.

Thanks for the replies guys, just wanted to reassure that my little sis was safe on the road! You know how it is.

Her spare happens to be a 155/70/13 which is weird as all the tyres on the car were 165/65/13 before we changed the front two. I'l get her a can of tyre weld in case one of the rears gets a puncture.