Will car pass MOT with different size tyres on

longwalks1

Got my MOT coming up and have 2 different sizes of tyres on my car, the sidewall measurement (eg 285/45/20), and on the front 285/40/20.
All tyres are practically new, can they fail it with a lower profile tyre on the front wheels?

I think some BMW's have differnt size tyres on??

paddedjohn

as long as both front are the same and both rear are the same then there shouldnt be a problem, are they a standard fit? as you say, some beemers do have different front and rear.

scheming_gypsy

it's fine as long as they're the same size on each axle as paddedjohn said

Austineer_2

britishboy wrote: »

I think some BMW's have differnt size tyres on??

You're quite right - many BMW, Mercedes and other prestige/sports cars have wider tyres on the back than on the front.

While yours aren't any wider, your fronts do roll slightly smaller than your backs.

And as the other posters have said, as long as the tyre sizes match on each axle, you're ok for MOT.

cyclonebri1

Austineer wrote: »

You're quite right - many BMW, Mercedes and other prestige/sports cars have wider tyres on the back than on the front.

While yours aren't any wider, your fronts do roll slightly smaller than your backs.

And as the other posters have said, as long as the tyre sizes match on each axle, you're ok for MOT.

Plus they won't even check, ;)

System

Tyre size is a part of the checks made on an MOT although only to confirm same sizes on an axle.

Are you aware of the following :

If you have the wrong size tyre on the axle that drives the speed sensor, then your speedometer will give you a false reading, so watch those speed limits

Have you informed your insurance company of the modification from the manufacturers standard fitment of tyre ? You should have.

Is the car under warranty, will it effect the warranty ?

Kilty_2

My current car has different profile tyres on the front and the speedo overreads a lot more than usual.

Wig

Yes they will pass, I had 14 inch on the rears and 13 inch on the fronts for two MOTs spaced a year apart, no problem.

longwalks1

BAA1 wrote: »

Tyre size is a part of the checks made on an MOT although only to confirm same sizes on an axle.

Are you aware of the following :

If you have the wrong size tyre on the axle that drives the speed sensor, then your speedometer will give you a false reading, so watch those speed limits

Have you informed your insurance company of the modification from the manufacturers standard fitment of tyre ? You should have.

Is the car under warranty, will it effect the warranty ?

Cheers everyone, shwe flew through the MOT today! :T

BAA1 they are standard size wheels/tyres for the car, so no need to let the insurance company know thankfully

System

britishboy wrote: »

Cheers everyone, she flew through the MOT today! :T

BAA1 they are standard size wheels/tyres for the car, so no need to let the insurance company know thankfully

Good to here it passed.

I guess the difference in overall diameter between the 40 and 45 profiles must be negligable and within the tolerances used for the speedo etc.

It was only that when I've seen different size tyres specified by a manufacturer, it has been for wider tyres (and maybe rims) with a lower profile tyre which ends up with the same overall diameter, but your situation must be OK if the manufactuer specs list both sizes.

Woody._2

BAA1 wrote: »

Good to here it passed.

I guess the difference in overall diameter between the 40 and 45 profiles must be negligable and within the tolerances used for the speedo etc.

It was only that when I've seen different size tyres specified by a manufacturer, it has been for wider tyres (and maybe rims) with a lower profile tyre which ends up with the same overall diameter, but your situation must be OK if the manufactuer specs list both sizes.

Wider rims don't need a lower profile. It's larger diameter rims that need them.