Wrong profile tyres on rear, disaster?

[minghis]

So, after 'inheriting' a nice Mazda 6 I got it serviced yesterday.

One of the things they noticed was that it has wrong profile tyres on the rear.. should be 225/45 but it has 225/40's.. I've only had it a day or two so really hadn't noticed it myself. The fronts are correct.

Never had this before - should I get them changed for the right profile as soon as or is this something that can happen, and when it does is it the end of the world?

PH assistance would be appreciated.

[GreigM]

It'll make no noticeable difference. The car will sit about 5mm lower at the rear than it should, but apart from that you will be unaware of such a slight change. You could get that kind of difference in height between brands anyway even if they were marked the same.

[bennyboysvuk]

Just a thought, but would it affect traction control or ABS if it has them since the fronts may now be revolving at a different rpm to the rears?

[22rgt B Squadron]

These would be better suited to the front but even so as above it will make little difference to the handling but above all is perfectly legal and safe..

[T0nup]

Smoke em... Then change em if you want.

[Rollcage]

Oh dear, a fiery death awaits for sure!

[Captain Muppet]

GreigM said:

It'll make no noticeable difference. The car will sit about 5mm lower at the rear than it should, but apart from that you will be unaware of such a slight change. You could get that kind of difference in height between brands anyway even if they were marked the same.

5% of 225mm is 11.25mm, not 5mm.

[Level 7 Boss]

A few people with 350zs go with the wrong profile tyres, with generally no issues. If you're driving to the conditions and not beinga drift warrior you should be fine.

[GreigM]

Captain Muppet said:

GreigM said:

It'll make no noticeable difference. The car will sit about 5mm lower at the rear than it should, but apart from that you will be unaware of such a slight change. You could get that kind of difference in height between brands anyway even if they were marked the same.

5% of 225mm is 11.25mm, not 5mm.

I didn't say it was, I said the difference in how the car will sit is 5mm (so it's 5.625mm). What's important here, radius or diameter?

[mygoldfishbowl]

Captain Muppet said:

GreigM said:

It'll make no noticeable difference. The car will sit about 5mm lower at the rear than it should, but apart from that you will be unaware of such a slight change. You could get that kind of difference in height between brands anyway even if they were marked the same.

5% of 225mm is 11.25mm, not 5mm.

Not at the bottom of the tyre it isn't.

Edit. Too late.

[Captain Muppet]

GreigM said:

Captain Muppet said:

GreigM said:

It'll make no noticeable difference. The car will sit about 5mm lower at the rear than it should, but apart from that you will be unaware of such a slight change. You could get that kind of difference in height between brands anyway even if they were marked the same.

5% of 225mm is 11.25mm, not 5mm.

I didn't say it was, I said the difference in how the car will sit is 5mm (so it's 5.625mm). What's important here, radius or diameter?

Radius, obviously.

The height of the tyre sidewall is a percentage of the width, and it is a radial dimension.

[GreigM]

Captain Muppet said:

Radius, obviously.

The height of the tyre sidewall is a percentage of the width, and it is a radial dimension.

oops, ah, erm, yes.....always assumed the aspect ratio was diameter (without actually looking at the numbers to realise...)....as you were

[George7]

My ZT has 225 40s instead of 225 45s, presumably to save money as 40s are a good bit cheaper. I considered changing them for 45s when I first got the car, but as it rides and handles fine on the 40s, it seems like unnecessary expenditure.

[minghis]

UPDATE...

I have got them changed for the correct 45 series. Tyre chaps say it's a relatively common thing as 225/45/18's are an uncommon size and 40's would have been cheaper and more popular in terms of stock.

Even though it probably would have been OK to leave 'em on it would have been a constant 'issue' and just in case of any insurance problems or stuff like that for the sake of £300 they're gone.

[CoolHands]

that was a waste of 300 quid. Bet the tyres guys love you