Need help with tire sizes for my 1991 BMW 850I

[theforce]

Which tire size and brand (car will not be driven winter time) would you recommend for a 1991,850 18x10 MK1 Motorsport?
Also show I use same size for front and rear axles?
Thanks

[Pneill316]

Which tire size and brand (car will not be driven winter time) would you recommend for a 1991,850 18” MK Motorsport?
Also show I use same size for front and rear axles?
Thanks

Do you have a little more size specs for your MK’s, I’m assuming they are mk1’s? Staggered 9/11?

[cartoonz]

245/40/18 front
275/35/18 or 285/35/18 rear

[theforce]

MK1s
18x10,ET20.
Have 5mm spacers for the front to bring it to ET15.

Any recommended brand ?

Thanks

[theforce]

245/40/18 front
275/35/18 or 285/35/18 rear

Why differant sizes for front and rear if all 4 rims has the same 10 width ?

[cartoonz]

because you can?
Hey, if you want to put skinny tires on the rears, go for it. Does make rotating tires easier, but it wont look or perform as nice. The outer circumference stays within the required tolerances with the sizes I listed... note the profiles are different 40 vs 35...

[Dr. T]

Will a 10” wide wheel even fit on the front? Especially with the same/rear offset?

[Hyper]

As an example, narrowing to 9" would bring the ET to the original 20mm minus 1/2 of the change, ie net 7mm.
For aluminum I have used Eric Vaugh, currently hobbling around the top of LA, and I'm currently doing a pair of steel at Weldcraft, Livonia for $225/ea.

[theforce]

I will put 5mm spacers in the front to lower the ET to 15...

[mikae31]

I will put 5mm spacers in the front to lower the ET to 15...

10" wide wheel with et15 wont fit in the front. Original e31 mk's are 9,5 et5 front and there are just few mm tolerance to the shock towers. If you are putting 10" wide rim in the front your et has to be at least 0, maybe even et-5.

Square 10" setup will look stupid because front rims will stick out from fenders. It will also propably rub. Wrong choice.

[theforce]

So what Should I do ?

[TxGR8White]

Get the correct wheels for the car. With the E31, there aren’t really that many options, as all the wheels made for it are specific to the car. The E31 MK1’s are 9” wide for the front and 11” wide for the rears. Going 10” in the front will most likely rub, either on the strut or on the fender, depending on the choice of spacer size.

[mikae31]

Get the correct wheels for the car. With the E31, there aren’t really that many options, as all the wheels made for it are specific to the car. The E31 MK1’s are 9” wide for the front and 11” wide for the rears. Going 10” in the front will most likely rub, either on the strut or on the fender, depending on the choice of spacer size.

E31 specific mk's are,

9,5x18" et5 front. There are about 5mm gap between rim and shock tower.
11x18" et21 rear. There are about 6mm gap between rim and control arm.

This is pretty much perfect fitment to e31. 10" front might clear the shock tower with et0 but will stick out from fender and propably rub in turns.

[rotomoto712]

Just an FYI, with a 10" wheel and 245 tire, if you are running et5 and have static camber plates (a la Phoenix Motorsports), they should clear beautifully with no rubbing or fender rolling, even with a mild drop. This is what I am currently running.

[mikae31]

Just an FYI, with a 10" wheel and 245 tire, if you are running et5 and have static camber plates (a la Phoenix Motorsports), they should clear beautifully with no rubbing or fender rolling, even with a mild drop. This is what I am currently running.

How much space is there between rim and tower? Because mk1's 9,5" et5 is pretty close to tower (about 5-6mm) 10" rim is 0,5" wider wich means it is 6,35mm wider per side...

[TxGR8White]

are you referring to an E31, or your E38? - big difference. The issue comes when you try to turn the wheel, its not just the strut tube...

[rotomoto712]

How much space is there between rim and tower? Because mk1's 9,5" et5 is pretty close to tower (about 5-6mm) 10" rim is 0,5" wider wich means it is 6,35mm wider per side...

There is maybe 2mm of space. Just enough to slide a piece of cardboard between the two. The original wheel offset was ET20. With a 10mm spacer only the passenger side wheel rubbed (barely) on the strut tower. Additionally, I stepped up to a 15mm spacer and it cleared. I am running static camber plates, roll correction blocks, and spherical bearings in all front control arms. Perhaps this has an effect? Or variances in wheel/tire manufacturer? The wheels I am running are Beyern Munich, with Falken FK453 Tires. This is on my E31 btw, I no longer have an E38. No issues turning the wheel, as I have had several 140mph + passes on the Autobahns and no rubbing marks on the inner fender liner, fender or the wheel itself.

[mikae31]

There is maybe 2mm of space. Just enough to slide a piece of cardboard between the two. The original wheel offset was ET20. With a 10mm spacer only the passenger side wheel rubbed (barely) on the strut tower. Additionally, I stepped up to a 15mm spacer and it cleared. I am running static camber plates, roll correction blocks, and spherical bearings in all front control arms. Perhaps this has an effect? Or variances in wheel/tire manufacturer? The wheels I am running are Beyern Munich, with Falken FK453 Tires. This is on my E31 btw, I no longer have an E38. No issues turning the wheel, as I have had several 140mph + passes on the Autobahns and no rubbing marks on the inner fender liner, fender or the wheel itself.

Even though it works for you, this is not recommended. Wheels width is measured from the inner surfaces of the outer and inner edge. Thickness and shape of the inner edge changes from wheel to wheel and this means some wheel may clear the tower and some not.

I would like to know how bad your car is to drive with those tyres? Stretched 35 (?) series tyre, that cant be good.

[rotomoto712]

30 series actually, my summer wheels are 20", not a popular choice I know, but I like them. The ride is a somewhat harsher than with the 18" style 32s I run during the winter months, but not as much as many think. The steering response is however, noticeably sharper with the larger wheels, especially since they are actually a couple pounds lighter (multi-piece construction), than the factory style 32s and provide more tactile feedback. I'm sure the spherical bearing setup plays a large part, and honestly I wouldn't run anything larger than 18s without them.



Edit: my sincerest apologies, but I went back to check my front wheel, and they are actually 9." I was confusing my rear wheels which are actually 10.5." To the OP listen to the experts not me ��

[mikae31]

Edit: my sincerest apologies, but I went back to check my front wheel, and they are actually 9." I was confusing my rear wheels which are actually 10.5." To the OP listen to the experts not me ��

Now we are on the same page. 245 mounted on a 9" wheel sounds much better.

[rotomoto712]

Now we are on the same page. 245 mounted on a 9" wheel sounds much better.

Absolutely, it got me thinking a 245 on a 10" wheel is quite an extreme stretch, especially considering how the 9" wheels have a slight stretch with the 245s