mixing 245 rear and 215 fronts. Is it ok, safe@

[joyful]

Ts it safe to have 245s on the rear and 215's on the front.

AMG standard MB rims on a CLK320

 

[BaldGuy]

Yep no worries at all.....

 

[Carrsey]

My CLK has AMG rims with 225/40 front and 255/35 rear and that's from factory.

 

[rf065]

Maybe, maybe not. You need to post the exact tyre dimensions of both tyres including width/diameter & aspect ratio before anyone could tell you.

Russ

 

[joyful]

Maybe, maybe not. You need to post the exact tyre dimensions of both tyres including width/diameter & aspect ratio before anyone could tell you.

Russ

215/40/17 front and 245/40/17 rear. Original AMG MB rims

Is there any good reason to put 215's on the front (apart from being cheaper)

 

[rf065]

215/40/17 front and 245/40/17 rear. Original AMG MB rims

I think the fronts should be 225/45x17, unless someone knows different. I should have mentioned the wheel width is applicable too, i.e. are the wheels 7.5J front & 8.5J rear?

Russ

 

[joyful]

I think the fronts should be 225/45x17, unless someone knows different. I should have mentioned the wheel width is applicable too, i.e. are the wheels 7.5J front & 8.5J rear?

Russ

Unsure of the rims width. They are standard factory fit AMG 2001 CLK320 and 245/40/17's fitted at present front and back.

 

[rf065]

The wheel size will be stamped on the inside of one of the wheel spokes.
Usual Mercedes fitment is 225/45x17 on a 7.5J front and 245/40x17 on a 8.5J rear. The 215 & 245 you mentioned do not have the same rolling diameter.

(you really need to check the wheel rim width, a 245 needs at least an 8J rim, if fronts are only 7.5J then a 245 is too big)

Russ

 

[joyful]

The wheel size will be stamped on the inside of one of the wheel spokes.
Usual Mercedes fitment is 225/45x17 on a 7.5J front and 245/40x17 on a 8.5J rear. The 215 & 245 you mentioned do not have the same rolling diameter.

(you really need to check the wheel rim width, a 245 needs at least an 8J rim, if fronts are only 7.5J then a 245 is too big)

Russ

I will check the rims.

If the rolling diameter is different, I presume that affects speedo/revs/gearing. Is the pick up for the speed/revs on the rear axles?

 

[Bobby Dazzler]

Are the tyres already fitted?

I personally wouldn't run my car with with this combination. The diameter of the wheel and tyre is 30mm smaller than it should be, ie more than an inch!

That could cause problems for systems which monitor rotation of the wheels like ABS, ESP, and Cruise Control.

It won't be a recommended tyre size and so could cause complications in the event of an insurance claim.

 

[Bobby Dazzler]

I will check the rims.

If the rolling diameter is different, I presume that affects speedo/revs/gearing. Is the pick up for the speed/revs on the rear axles?

Yes almost 92mm smaller in rolling radius (4.81%)

 

[Howard]

The difference in price between 215's and 225's is so little as to be not worth worrying about surely ?

 

[Paul/]

Using this online tyre/wheel size calculator gives a 12mm difference in the external radii.

Tyre Size Calculator - Changing Tyres - Etyres

...doesn't sound much but perhaps even such a small lowering of one end of a vehicle shift the front/rear load distribution and so affect handling and braking?

Similarly, would having 30mm wider tyres on the rear noticeably change handling?

...so should suspension be adjusted to allow for these changes?

..and even if these factors were negligible, might an insurance company, as a previous post suggests,be able to void a claim for running non-standard/approved tyre/wheel combinations?

 

[renault12ts]

215/40/17 front and 245/40/17 rear. Original AMG MB rims

Is there any good reason to put 215's on the front (apart from being cheaper)

Totally wrong.

When you have narrower tyres on the front you must increase the aspect ratio so that the diameter front and rear are the same.

Your fronts have a tyre wall depth of 83mm, and the rears 98mm...so the rears are much taller than the front. Nothing will work properly with that set up.

It is less about the actual width of the tyres and all about the diameter.

 

[joyful]

Totally wrong.

When you have narrower tyres on the front you must increase the aspect ratio so that the diameter front and rear are the same.

Your fronts have a tyre wall depth of 83mm, and the rears 98mm...so the rears are much taller than the front. Nothing will work properly with that set up.

It is less about the actual width of the tyres and all about the diameter.

Does that mean that 245/40/17 rear and 215/40/17 front should not be mixed? That the wall diameter would need to be increased on the 215 front to match the rear?

 

[redbaron]

You should have 225/45 on the front.

the 215's are not suitable. They will affect the vehicles safety systems and invalidate your insurance as they are outside manufacturers specs. The wheels speed "differences" will affect ABS / ABD / ASR / ESP etc.

 

[Carrsey]

Does that mean that 245/40/17 rear and 215/40/17 front should not be mixed? That the wall diameter would need to be increased on the 215 front to match the rear?

I would say so, which is why like mine the fronts are 225/40/18 but the rear are 255/35/18, to bring the radius to the same level..

 

[joyful]

You should have 225/45 on the front.

the 215's are not suitable. They will affect the vehicles safety systems and invalidate your insurance as they are outside manufacturers specs. The wheels speed "differences" will affect ABS / ABD / ASR / ESP etc.

Thank you for the info. That was what I was feeling.

I presume 245/40/17 all round is perfectly safe and sensible and the best option.

 

[redbaron]

Thank you for the info. That was what I was feeling. I presume 245/40/17 all round is perfectly safe and sensible.

not on 7.5" rims

you need the narrower fronts unless you fit wider rims.

 

[developer]

This is what you should have - expand the tyre fitment section.
AMG alloy wheels | Genuine new 17" AMG III | fits Mercedes CLK Class 208 | Alloy Wheels Direct Ltd

I would imagine if you run undersize tyres your insurance company may walk in the event of an accident.