225/55/16 Rear and 215/55/16 Front

[91pat]

Hi Guys,

I have a w210 320cdi for the winter and just bought two winter tyres for the rear. Only thing is the standard size is 215 55 16 ( which will remain on the front) and the new rears will be 225 55 16. So slightly bigger and wider on the rear. I have not fitted them yet.

Does anyone know if this will affect the the traction control / abs / cruise control?? I have read as many threads as I could find some saying a slightly higher rear won't make a difference unless at motorway speeds, others saying it will throw a serious wobbly at any speed!

Any help appreciated. Won't get them mounted if it will cause issues.

Thanks

 

[renault12ts]

Yes, it will. The different size tyres will make the car think the front and back are travelling at different speeds. Your CC will not work at higher speeds...and other effects may be felt too.

 

[flango]

If my mental arithmetic is correct I reckon that gives you just less than a 2% rolling diameter difference between front and rears. I'm not sure what the tolerances are for the sensors that control abs/cruise/traction If someone knows that you could do the maths properly and take an educated decision.

My gut feeling at the moment says no though I would not do it.

 

[Robster_1981]

I don't know if I am missing something here, but the first number denotes the width of the tyre, so a 225 is 10mm wider than a 215. If the profile '55' and diameter '16' are the same, then the overall outside diameter of the tyre is exactly the same

Lot's of Mercs, BMW's etc have staggered wheels with wider rims on the rear, so it will have no effect on the traction control etc AFAIK

 

[renault12ts]

If my mental arithmetic is correct I reckon that gives you just less than a 2% rolling diameter difference between front and rears. I'm not sure what the tolerances are for the sensors that control abs/cruise/traction If someone knows that you could do the maths properly and take an educated decision.

My gut feeling at the moment says no though I would not do it.

When my rear tyres have worn down to a certain point...it effects the CC.

I suspect starting with a tread 5.5mm higher than standard will do the same...especially if the fronts are not new and the rears are.

 

[renault12ts]

I don't know if I am missing something here, but the first number denotes the width of the tyre, so a 225 is 10mm wider than a 215. If the profile '55' and diameter '16' are the same, then the overall outside diameter of the tyre is exactly the same

Lot's of Mercs, BMW's etc have staggered wheels with wider rims on the rear, so it will have no effect on the traction control etc AFAIK

The profile is a percentage of the width, so if the tyre is 10mm wider, then it is also 5.5mm (55% of 10mm) higher on the side wall. 16" is the diameter of the wheel....the diameter of the tyre is thus greater.

And thus your last sentence (in fact all of your statement) is wrong because although cars do have staggered set ups, the rears have a lower profile ratio, to maintain the same diameter of the tyre.

My wife's car, a RAV4 has 215 tyres on 16 inch wheels. But because the profile ratio is 70...it's a much much taller tyre.

 

[flango]

I don't know if I am missing something here, but the first number denotes the width of the tyre, so a 225 is 10mm wider than a 215. If the profile '55' and diameter '16' are the same, then the overall outside diameter of the tyre is exactly the same

Lot's of Mercs, BMW's etc have staggered wheels with wider rims on the rear, so it will have no effect on the traction control etc AFAIK

The profile is different 55 is 55% of the width so 55% of 215 is 118.25 whilst 55% of 225 is 123.75. You have to times these by two and add to the diameter of the wheel. This gives different rolling diameters.

Although lots of MB run staggered wheel set ups, the rolling diameter of the front and rears are exactly the same so not to affect cruise or ABS.


* Renault12TS beat me to it

 

[91pat]

I thought height of tyres was 225 x 55%. So Difference will be 10mm x .55 or 5.5mm. If that's correct? Fronts will be relatively new, and the winter rears have some wear on them.

May be better off selling them and getting correct sizes.

Thanks

 

[renault12ts]

I thought height of tyres was 225 x 55%. So Difference will be 10mm x .55 or 5.5mm. If that's correct? Fronts will be relatively new, and the winter rears have some wear on them.

May be better off selling them and getting correct sizes.

Thanks

Correct, the tyre wall is 5.5mm higher...the tyre 11mm higher.

You may be ok because the fronts are newer than the back.

 

[sinewave]

All that aside it aint a good idea to mix summer and winter boots on the same vehicle.

 

[Robster_1981]

The profile is a percentage of the width, so if the tyre is 10mm wider, then it is also 5.5mm (55% of 10mm) higher on the side wall. 16" is the diameter of the wheel....the diameter of the tyre is thus greater.

And thus your last sentence (in fact all of your statement) is wrong because although cars do have staggered set ups, the rears have a lower profile ratio, to maintain the same diameter of the tyre.

My wife's car, a RAV4 has 215 tyres on 16 inch wheels. But because the profile ratio is 70...it's a much much taller tyre.

Well you learn something new every day
I've been buying tyres for years not realising that , so I'm glad I stuck my oar in now

 

[hotrodder]

Personally i wouldn't have thought it'd be a big enough difference to confuse the ABS etc... was recently running about with 205/60r15 on the front and 225/45r17 on the back for a week or so (waiting for a pair of 17" tyres to arrive and getting around to fitting them etc) which have a similar difference in diameter and all of them were at ~ 5mm of tread. ABS didn't throw a spaz however...

As said mixing a pair of winters with a pair of summer tyres ain't a good idea as it's gonna result in very different grip levels front to rear

 

[91pat]

Thanks, I might give it a go anyway as I have spare steels to throw them on to. I would only be running them if snow actually comes, so surely it would be better to have two snow tyres rather than none?

 

[GP801]

Thanks, I might give it a go anyway as I have spare steels to throw them on to. I would only be running them if snow actually comes, so surely it would be better to have two snow tyres rather than none?

No it would not. Winter tyres on the rear with summers on the front not good. May have drive/traction but limited steering/braking. Recipe for trouble.

 

[Rory]

No it would not. Winter tyres on the rear with summers on the front not good. May have drive/traction but limited steering/braking. Recipe for trouble.

It's a bit better than the other way around though that you hear about quite a bit - front wheel drive owners putting winter's on the front only. They can get going OK, but then they brake and the back overtakes the front!

 

[renault12ts]

It's a bit better than the other way around though that you hear about quite a bit - front wheel drive owners putting winter's on the front only. They can get going OK, but then they brake and the back overtakes the front!

But it should be ok...cause most braking is at the front in any case..?

 

[hotrodder]

Think about the idiots that park their back wheels on mcdonalds trays to go tea tray 'drifting' around the local carpark in their FWD shopping trolleys. Back wheels may only be 'along' for the ride with FWD but if they've not got any grip it makes things interesting when you're expecting it, dangerous when not/having to take evasive action

I'm sure when winter tyres became the 'in thing' after getting a bit more snow than usual the other year there was a vid* doing the rounds comparing 4 x summer tyres to 4 x winter tyres and 2 of each. 2 of each is the least predictable... terminal understeer with RWD and terminal oversteer (including pirouettes when braking in a straight line) with FWD


* A proper tyre test, not someone larking about