What size tyres can I put on M5 wheels?

[DanE34M5]

Hi, so I recently bought these 8J17 & 9J17 throwing star wheels for my E34 M5. It now has 9J18 Racing Dynamics wheels which look awesome but I want everything back to 100% genuine BMW. I quite like the idea of stretched tyres, so I'm thinking 205/50 front and 225/45 rear. Would that work? Thanks

[E-bmw]

DanE34M5 said:

I want everything back to 100% genuine BMW. I quite like the idea of stretched tyres]

Sorry, I didn't realise BMW fitted the wrong size tyres.

[mmm-five]

If you're going for originality, then you probably already know the original tyres sizes. But you probably won't find any new Michelin MMX2 tyres anyway.

Therefore whilst your proposed sizes provide a tyre that is not far off the overall rolling circumference of the originals, the suitability/sensibility/aesthetics may not be:

• The recommended width for a 8J is 215-245, with a recommendation of 235-245.
• The recommended width for a 9J is 235-265, with a recommendation of 245-255.

So in both cases you're 10mm below the minimum, and you have to take into account the profile of the sidewall and the angle of stretch, as this will also reduce the height a little (due to it no longer being completely upright).

As to whether this is sensible or not, or even just good looking, then I'll leave that to your own opinion (but no it's not)!

Edited by mmm-five on Thursday 9th February 09:07

[DanE34M5]

If I go with the minimum recommended width, due to tyre availability I'll have to stick 215/45R17 on the 8J wheels and 235/45 on the 9J wheels. The overall diameter difference would be 18mm between front and back. Sounds like a lot to me. Thoughts?
For clarification: I want Goodyear Asy6 or Michelin PS5 tyres.

[mmm-five]

You could run a 235/45r17 on front & rear as a 'square' set-up...albeit on different width rims...although to keep them to a closer (i.e. with 1%) rolling radius you'd need a 235/40r17.

Is there any reason (other than cosmetic) that you don't want to run OE sizes on your OE wheels?

I quite liked the ride/handling/looks of the OE sizes on mine (here it is in its track mode without covers)...


...and with covers...

[DanE34M5]

mmm-five said:

You could run a 235/45r17 on front & rear as a 'square' set-up...albeit on different width rims...although to keep them to a closer (i.e. with 1%) rolling radius you'd need a 235/40r17.

Is there any reason (other than cosmetic) that you don't want to run OE sizes on your OE wheels?

I quite liked the ride/handling/looks of the OE sizes on mine (here it is in its track mode without covers)...


...and with covers...

235/40 would be perfect, but it's sadly not available from Goodyear or Michelin

[mmm-five]

DanE34M5 said:

235/40 would be perfect, but it's sadly not available from Goodyear or Michelin

Well, the standard front (and square) set-up used a 235/45r17...which is available as a GY F1A6, but the Michelin PS5 may just be a little too new to be available in this size.

Neither the PS5 or the F1A6 is available in the standard 255/40r17 rear though

But I have a similar problem with getting matching tyres for my Z4MC in the standard staggered sizes.

Edited by mmm-five on Thursday 9th February 20:19

[DanE34M5]

I think I've worked out a good compromise. 225/50R17 front and 245/45R17 back. The diameter difference is only 0.8% and these tyres are available.

[mmm-five]

DanE34M5 said:

I think I've worked out a good compromise. 225/50R17 front and 245/45R17 back. The diameter difference is only 0.8% and these tyres are available.

Between front & back they're less than 1% out, but they're both about 2-3% bigger than OE tyres, so watch out for catching arch-liners and other components (width won't be the issue as you've gone narrower, just the extra height).

[DanE34M5]

mmm-five said:

DanE34M5 said:

I think I've worked out a good compromise. 225/50R17 front and 245/45R17 back. The diameter difference is only 0.8% and these tyres are available.

Between front & back they're less than 1% out, but they're both about 2-3% bigger than OE tyres, so watch out for catching arch-liners and other components (width won't be the issue as you've gone narrower, just the extra height).

At the rear there's a 10mm difference, but since I'm replacing a 265/35R18 with a 245/45R17 at the wheel arch there should be no significant difference.

[mmm-five]

DanE34M5 said:

At the rear there's a 10mm difference, but since I'm replacing a 265/35R18 with a 245/45R17 at the wheel arch there should be no significant difference.

True, and the actual tyre might make more of a difference than the nominal size of the tyre, for example I always found Pirelli P-Zeros Rossos to be slightly larger (<5mm taller) than the Michelin equivalents.

[DanE34M5]

Ordered the tyres, will be fitted on Saturday. I`ll post some pictures once it`s done. Thanks for the help!

[DanE34M5]

Done. I'm pretty happy with the end result.

[mmm-five]

Much better, and the lip is even deeper than I remember, but I believe the longer point on the throwing star faced forwards (as per BMW press photos below), unless you've got 4 LH throwing star covers?

[DanE34M5]

mmm-five said:

Much better, and the lip is even deeper than I remember, but I believe the longer point on the throwing star faced forwards (as per BMW press photos below), unless you've got 4 LH throwing star covers?

I'll have to check that. I hope I'll just have to switch them left to right.

[DanE34M5]

DanE34M5 said:

mmm-five said:

Much better, and the lip is even deeper than I remember, but I believe the longer point on the throwing star faced forwards (as per BMW press photos below), unless you've got 4 LH throwing star covers?

I'll have to check that. I hope I'll just have to switch them left to right.

I've got 3 lefties and 1 righty (:

[mmm-five]

DanE34M5 said:

I've got 3 lefties and 1 righty (:

No-one (else) will notice