[Tunna_uk]

Hello
Trying to find out if I can get away with a different tyre size on my spare set of alloys. They are E36 Motorsport staggered alloys. The idea is to try and source some winter tyres either now or for next winter......and use them over winter only......

Its the rears I am having difficulty with. They are 8.5 J 17 inch. They currently have the E36 M3 size 245 40 17 tyres on.

This seems an unusual size for finding winter tyres. I was wondering if the wheel would take a 235 tyre or a even a 225, to make it 225 all round. Or would the tyre be too stretched?

Or could it take a wider tyre say 255 40 17.

Any help appreciated.
Thanks

[willhollin]

What size are your fronts?

[Tunna_uk]

they are 225 45 17 but the wheels on the front are 7.5 J 17

[MEGA]

225 will be fine on both 7.5j and 8.5j.

[Hotcoupe]

225 tyre would fit a 8.5J rim no probs.

[Ham09]

Originally Posted by Hotcoupe

225 tyre would fit a 8.5J rim no probs.

Actually this depends on the specification of the tyre manufacturer. I asked Vredestein about there Wintrac Xtreme tyres and they said the 225/45R17 would not be suitable for a 8,5J 17" rim. I guess it depends how flexible the tyre is to stretch.

They recommend the 255/40R17 on 8,5J rear wheels on my motor.

[Hotcoupe]

Originally Posted by Ham09

Actually this depends on the specification of the tyre manufacturer. I asked Vredestein about there Wintrac Xtreme tyres and they said the 225/45R17 would not be suitable for a 8,5J 17" rim. I guess it depends how flexible the tyre is to stretch.

They recommend the 255/40R17 on 8,5J rear wheels on my motor.

Fair enough, seems strange though given the standard tyre size for a 8" rim (front) on a BMW is 225 and 255 on a 9" rim (rear).

Personally I'd be going for a narrower tyre than the norm for a winter tyre, especially on the driven wheels.

[R80TER]

on a tangent to this topic (apologies OP!) i have a set of Z4M coupe wheels in my garage, same tyre sizes as my standard M sport, but could i fit these wheels to my car with winter tyres on? i am an idiot when it comes to offsets etc... they are the same wheels as this:

[Hotcoupe]

Originally Posted by R80TER

on a tangent to this topic (apologies OP!) i have a set of Z4M coupe wheels in my garage, same tyre sizes as my standard M sport, but could i fit these wheels to my car with winter tyres on? i am an idiot when it comes to offsets etc... they are the same wheels as this:

ET47 (Z4), 10mm spacers takes it to ET37, job done.

[Ham09]

Originally Posted by Hotcoupe

Fair enough, seems strange though given the standard tyre size for a 8" rim (front) on a BMW is 225 and 255 on a 9" rim (rear).

Personally I'd be going for a narrower tyre than the norm for a winter tyre, especially on the driven wheels.

Which wheels do you have for 9j at the rear? Both my OEM sets (R17 and R18) are 8,5J at the rear. I was of the same opinion as you thinking narrower was better for the winter (increased load pressure etc), but Vredestein recommended the 255 tyre on the rear which is the BMW stock size according the inside of the car door anyway.

From what I have read (and I feel like I have become flippin tyre geek in the last week reading up on winter tyres lol) if you go outside of the recommended tyre size for the rim (either too narrow or too wide) apart from stretching the sidewall, the tread surface distorts convex/concave depending which way you go, therefore reducing your grip and creating uneven tyre wear shortening the life of the tyre. I'm only basing this on what I have read but it seems plausible

[Tunna_uk]

Can someone say yeah or Nah for the 225 on a 8.5J wheel please???? Don't want to get it wrong.

Thanks

[Hotcoupe]

Originally Posted by Ham09

Which wheels do you have for 9j at the rear? Both my OEM sets (R17 and R18) are 8,5J at the rear. I was of the same opinion as you thinking narrower was better for the winter (increased load pressure etc), but Vredestein recommended the 255 tyre on the rear which is the BMW stock size according the inside of the car door anyway.

From what I have read (and I feel like I have become flippin tyre geek in the last week reading up on winter tyres lol) if you go outside of the recommended tyre size for the rim (either too narrow or too wide) apart from stretching the sidewall, the tread surface distorts convex/concave depending which way you go, therefore reducing your grip and creating uneven tyre wear shortening the life of the tyre. I'm only basing this on what I have read but it seems plausible

The 225 wheel (MSport option) are 19x8 front with a 225 tyre and 19 x 9 rear with a 255 tyre.

I won't argue with what Vredestein are advising in regards their tyres,they make them so they should know, but it seems there reasoning is based on the OEM size for your wheel, not the limitations of their tyres.

I'd still be wanting a narrower tyre than the norm on the driven wheels for snow tyres and we are not talking about a massive difference in tyre sizes here.
Rear wheel drive & wider tyre = spreading more of the unsprung weight = less traction.

I still stick by what I originally said - a 225 tyre will fit a 8.5J rim and with no detriment to the tyre.

[Tunna_uk]

I won't argue with what Vredestein are advising in regards their tyres,they make them so they should know, but it seems there reasoning is based on the OEM size for your wheel, not the limitations of their tyres.

I'd still be wanting a narrower tyre than the norm on the driven wheels for snow tyres and we are not talking about a massive difference in tyre sizes here.
Rear wheel drive & wider tyre = spreading more of the unsprung weight = less traction.

I still stick by what I originally said - a 225 tyre will fit a 8.5J rim and with no detriment to the tyre.[/QUOTE]

I know what I'll do. I will order two 225 45 17 and try them on the rear wheels for fit.
If no good, they can go on the front wheels which are currently fitted with that size anyway. Then I will look for a wider tyre for the backs.
Thanks for help guys

[Ham09]

Originally Posted by Tunna_uk

I know what I'll do. I will order two 225 45 17 and try them on the rear wheels for fit.
If no good, they can go on the front wheels which are currently fitted with that size anyway. Then I will look for a wider tyre for the backs.
Thanks for help guys

Let me know how you get on Tuna_uk. I've got a back order with Camskill for the 255 on my rear wheels but they don't know when they will come in. Hopefully in 2 weeks.

If the 225's Wintracs work out ok on your 8,5j rims I might just do the same. There seems to be more stock around in that size

[ed335d]

Originally Posted by Ham09

Let me know how you get on Tuna_uk. I've got a back order with Camskill for the 255 on my rear wheels but they don't know when they will come in. Hopefully in 2 weeks.

If the 225's Wintracs work out ok on your 8,5j rims I might just do the same. There seems to be more stock around in that size

I bought 245 for my 8.5j rears and 225 for the 8j fronts. Kwikfit screwed up and put the wrong tyres on the wrong wheels and the 225 looked stretched on the 8.5j