Style 135 and tire-size

[Highstreet]

I believe my Z4 2.5 2003 has BMW Style 135 rims. Both on the front and the back the tires have size 225/40 R18. But if I look in the original Z4-manual at the tire-table it seems that on the front you should have 225/40 R18 but on the back 225/35 R18.

I don't understand why my Z4 is configured this way. Would it be possible to put 225/35 R18 tires on the back when the tires have to be changed? Or wouldn't that size fit my Style 135 rims?

 

[mr wilks]

You need to remove a rear to see what width it is . There are many sets of these that are the same width front & rear . Even if they are you can still fit a wider tyre to rear if you choose

 

[Highstreet]

I see, thanks.
Would it be better to fit 255/35 R18 on the rear? I presume BMW mentions this for a reason in the manual? Or am I o.k. with the current size on the rear?

 

[mr wilks]

I see, thanks.
Would it be better to fit 255/35 R18 on the rear? I presume BMW mentions this for a reason in the manual? Or am I o.k. with the current size on the rear?

All depends on the actual wheel specs . I would suspect original wheels with wrong tyres on rear for financial saving but first step is remove a rear & look for the j & et numbers

 

[ben g]

I believe my Z4 2.5 2003 has BMW Style 135 rims. Both on the front and the back the tires have size 225/40 R18. But if I look in the original Z4-manual at the tire-table it seems that on the front you should have 225/40 R18 but on the back 225/35 R18.

I don't understand why my Z4 is configured this way. Would it be possible to put 225/35 R18 tires on the back when the tires have to be changed? Or wouldn't that size fit my Style 135 rims?

I think you've misread the manual. The rears would be either 225/40/18 (non staggered set up) or 255/35/18 (staggered set up).

As said, only way to be sure is to remove a rear wheel and on the rear of the spokes, it will tell you how wide the wheel is. It should be 8.5j, which would then require a 255/35/18 tyre. If it's 8j, then you can stick with the 225/40/18.

 

[Highstreet]

I think you've misread the manual. The rears would be either 225/40/18 (non staggered set up) or 255/35/18 (staggered set up).

You’re right, I meant 255/35 R18.

I can’t take the wheel off myself but I’ll have it checked during the next service.
In the mean time I assume it’s best to pressurize the rear tires with 2,3 bar as stated in the manual?

 

[srhutch]

I think you've misread the manual. The rears would be either 225/40/18 (non staggered set up) or 255/35/18 (staggered set up).

You’re right, I meant 255/35 R18.


I can’t take the wheel off myself but I’ll have it checked during the next service.
In the mean time I assume it’s best to pressurize the rear tires with 2,3 bar as stated in the manual?

If you have wider wheels on the rear, but the same 225's as on the front there should be much more lip of the wheel visible as the tyre is stretched further. If they look the same you probably have a set of fronts all round as Mr Wilks said, or a set of reps.

 

[Highstreet]

The tires seem to fit exactly the same on the front- and rear-rims. So I assume the rims are the same, but I’ll have it checked at the next service.

 

[Anonymous]

If they're exactly the same there's a good chance they're reps, or someone's put together a set of 4 fronts, which isn't actually that uncommon.

I've got a strange set of wheels I use through the winter. They're a square setup and only 3 of them are genuine!

 

[Mr Tidy]

You’re right, I meant 255/35 R18.

I can’t take the wheel off myself but I’ll have it checked during the next service.
In the mean time I assume it’s best to pressurize the rear tires with 2,3 bar as stated in the manual?

If you have a standard set of 135Ms they will be staggered, as in 8J front and 8.5J rear. Which is why the rears have wider tyres.

I can't recall the recommended pressures, but they are on a plate that you see when you open the driver's door.

But bear in mind these pressures are for run-flat tyres - they may not be the best if your car has had non run-flats fitted.

 

[Scooba_Steve]

For me, 3.0si so a little lighter up front, 33F 35R work well on 108s (staggered 18s). I use the same on 17 square for winter.