E38 M Par tire size on E34

[///Sniper535]

What do you guys think of this tire size set up on stock suspension?


FRONT: 245/40/18
REAR: 275/35/18

[BMWDriver]

Are you sure the 275's will fit ? Do you expect to run spacers ? M-Pars are pretty hot. You'll be getting one sexy ride.

[///Sniper535]

no spacers, i'm trying to see what will be best for the rear 9.5" wide wheels.

[BMWDriver]

The bmwe34.net website suggests 265 35 18 as the largest 18 inch wheel for the e34, and 275 30 19 for 19 inch. The offset of the e38 is 23mm, where the e34 is 20mm except for the M5. This means the wheels of the e38 would be about 1/8" farther in. And since the wheel is 9.5 inch wide, this brings it closer to the struts.

I have not test fitted any, so I'm no real help except for the theory. It would be ideal to have someone who has 'em to chime in, or for you to test fit the rim without rubber at least.

You might try this forum:
http://forums.bimmerforums.com/forum/index.php

There's a specific thread for wheels, and another for the e34 that is much more active.

[Maximabello]

I have 265/35 on my rear m parallels. I had to roll the rear fenders to avoid rubbing with weight in the car.

[///Sniper535]

Can someone tell me what would be better for the 8"/9.5" staggared set up.

245/40/18 all around
or
235/40/18(F) & 255/35/18(R)

Thanks, I cant make a decision, it seems though that the 245/40/18s are more common tires.

[Interceptor]

Can someone tell me what would be better for the 8"/9.5" staggared set up.

245/40/18 all around
or
235/40/18(F) & 255/35/18(R)

Thanks, I cant make a decision, it seems though that the 245/40/18s are more common tires.

Neither.

I have staggered E39 M-Pars (8"/9") and use 235/40-18 front and 265/35-18 rear. I suggest you use the same, since I don't experience any rubbing and 255/35 has smaller diameter than stock.

Here's how it looks like on my car:
http://i384.photobucket.com/albums/oo285/scikes/090808_190737.jpg

[///Sniper535]

Isnt the offset different vs E38 and E39 M Parallels?

[Interceptor]

Isnt the offset different vs E38 and E39 M Parallels?

E39:
- front: 235/40-18 ET20
- rear: 265/35-18 ET24

E38:
- front: 235/50-18 ET13
- rear: 255/45-18 ET25

As you can see, in the front there is 7 mm difference, and in the rear only 1 mm. I'm not sure, but you might need spacers in the front. If there's rubbing in the rear, you can always roll the inside of your fenders.

[bubba966]

Factory tire size on E34 M-Pars (18x8et20 & 18x9et22) was 245/40/18 all around. Unless 245 is too narrow for the 9.5" width E38 rim I'd run 245/40/18 on all corners.

[BMWDriver]

ET13 actually brings the wheel out further, so spacers would only increase that. ET13 should be fine, some E34 owners have had ET0 and ET10 on their ride with no reported problems. So you'll be just fine.

Worse case scenario with the 265s would be that you add 5 mm spacers if you get some rubbing. Seems very likely that you won't get that problem.

[///Sniper535]

Ok, so what about tire brand? any good recommendations?

[bubba966]

Michelin Pilot Sport A/S+ or Michelin Pilot Sport PS2 depending on your weather conditions.

[BMWDriver]

I personally have Continental ExtremeContact 4 seasons which really impressed me in the rain; I run them in 235 45R 17. I sigh when I think I'll be going on 205s in the winter...

[Interceptor]

I personally have Continental ExtremeContact 4 seasons which really impressed me in the rain; I run them in 235 45R 17. I sigh when I think I'll be going on 205s in the winter...

205s are good for rain and/or snow since they tend to resist aquaplanning better and make more pressure per square inch of the contact area.

[BMWDriver]

Yes, I'm aware. I'll miss the cornering performance of the 235s... ;)

[///Sniper535]

back to my other question, why is 245/40/18 all around better than 235/40/18 & 255or256/35/18?

[Interceptor]

back to my other question, why is 245/40/18 all around better than 235/40/18 & 255or256/35/18?

It's not. The M5 has thicker sway bars so wider rear tires would induce understeer since the rear would grip better. The tire choice really depends on your suspension setup and the purpose of your car. I would stick to the E39 tire setup unless you track your car ;)

[BMWDriver]

There is also going to be an influence on your speedometer and mileage readings, depending on the overall diameter of the tire you choose.

I suggest you give this a good read : http://www.bmwe34.net/Wiki/tiki-index.php?page=Wheels

And here for a calculator : http://www.powerdog.com/tiresize.cgi

[bubba966]

It's not. The M5 has thicker sway bars so wider rear tires would induce understeer since the rear would grip better. The tire choice really depends on your suspension setup and the purpose of your car. I would stick to the E39 tire setup unless you track your car ;)

I think he's got thicker sways on his 535 if I'm remembering right.

But yes, wider rears are usually tried out by people that have M5's. And hanging out on the M5 board for quite some time has shown that they find their cars to be more neutral handling with a non-staggered tire setup.

There's no need for rubber wider than 245 as far as traction is concerned. That M30 isn't producing enough torque to easily overpower decent or good tires of 235 or 245 widths.

You don't have to track your car to feel the effects of understeer...

[///Sniper535]

I did upgrade to M5 sway bars and bushings. I think I will go with the non-staggard tire setup. Ive done the tire size calculations and it will be fine, not a significant difference.