ASK ALL WHEEL/TIRE FITMENT QUESTIONS HERE - The Official Wheel/Tire Fitment Thread

[Mystikal]

Hi guys. My name is Jay. I've been around this forum and many other over the years, studying E30 wheel and tire fitment since the late 90s. Many years ago I started this thread to help people out with one-on-one fitment advice, and for whatever reasons I'm still keeping up with it. I actually stopped driving an E30 4 months after starting this thread but the knowledge is still there. Go ahead and ask away, or search the thread for info that may help you along the way to proper fitment.

Also, a plug. I own a BMW service shop in the Toronto area, look us up if you're local. Stance Factory. Facebook.

When asking, please include: Year, Model, Suspension, All Relevant Wheel Data (Diameter, Width, Offset, Bolt Pattern, etc), Tire Size, anything that could possibly affect my answer. When it doubt, tell me. And do not PM me, I will ignore you. :)

[Van Westervelt]

Understandably, 17's will fit in general. My question is about rubber. I have 17x7's, 17x7.5's, and 17x8's.

17x7's get 215/40r17 ET27-20 works perfectly
17x7.5's get 215/40r17 ??? (225/40r17 non existant in any variety)
17x8's get 235/40r17

These are going onto a facelift model with lower rear arches and IE3 springs on billie sports. Anyone have any knowledge about the bold? I have arches rolled, do I need to pull them too? Any help or suggestions

[Jean]

Thank you. I'll go ahead and paste your response to my question here, I am sure this is probably a popular wheel selection.

"With 15x8 ET20 wheels and 225 tires, there is a slight chance you will need tiny spacers to clear the front struts. Like 3mm. This is totally dependent on the size of the curb protector in the tire, if there is any.

With 16x8 ET20 wheels and 225 tires, you will not need any spacing. This is due to the inclination of the struts, there is more room for larger wheels on the inside. You can get away with 225/50/16 if you have semi-extensive fender work (a member here who recently changed his username from Mtriple had that size R-comp on his white track car)."

With either Rota wheel, fender rolling will be required all around.

Q: Do you suggest a 225/45 tire for the 16x8 wheel will that also require semi-extensive fender work (could you also elaborate on this, to make sure we understand what it will take) ?

Would it make sense to go with ET10-15 on a 8" wheel instead of ET20 instead of running spacers or adapters and get more clearance for wider 225 tires. I understand that not all tires of the same size measure the same in width (potenzas on my brothers s2k come to mind).

In 15" tire size I am looking at Toyo t1r in 205 55 15 and 225 50 15, Hankook ventus rs2 z212 in 225 50 15.

In 16" size - T1r in 205 50 16 and 225 45 16. Falken Azenis rt615 is also an option in 215 45 16 and hankook ventus rs2 z212 in 205 50 16, 215 45 16 and 225 45 16.

[Mystikal]

Understandably, 17's will fit in general. My question is about rubber. I have 17x7's, 17x7.5's, and 17x8's.

17x7's get 215/40r17 ET27-20 works perfectly
17x7.5's get 215/40r17 ??? (225/40r17 non existant in any variety)
17x8's get 235/40r17

These are going onto a facelift model with lower rear arches and IE3 springs on billie sports. Anyone have any knowledge about the bold? I have arches rolled, do I need to pull them too? Any help or suggestions

The beautiful thing about 17's is that you have a lot of room on the inside due to the angle of the struts. This is why people with 17's and 18's can run 255's and other scary sizes, while people with 15's are stuck with 225's.

Now, your wheel specs are a little vague. Are the 17x7.5 and 17x8 wheels the same offset range as the 17x7 ET20-27 you mention? Let me know what your possible offset choices are, and I can tell you the optimal offset for each width. If you just want a general range, tell me.

[Mystikal]

Q: Do you suggest a 225/45 tire for the 16x8 wheel will that also require semi-extensive fender work (could you also elaborate on this, to make sure we understand what it will take) ?

Would it make sense to go with ET10-15 on a 8" wheel instead of ET20 instead of running spacers or adapters and get more clearance for wider 225 tires. I understand that not all tires of the same size measure the same in width (potenzas on my brothers s2k come to mind).

In 15" tire size I am looking at Toyo t1r in 205 55 15 and 225 50 15, Hankook ventus rs2 z212 in 225 50 15.

In 16" size - T1r in 205 50 16 and 225 45 16. Falken Azenis rt615 is also an option in 215 45 16 and hankook ventus rs2 z212 in 205 50 16, 215 45 16 and 225 45 16.

Yes, I recommend a 225/45/16 tire for the 16x8 ET20 Rota Slipstreams. To fit that size, one would only need to extensively roll the fender lips front and rear until the inner wheel has no protruding metal. I've seen the same setup with half-assed rolled fenders not work properly at all, a fairly aggressive rolling (although, no visible change on the exterior of the fender) is necessary to fit them.

My extensive fender work note was regarding 225/50/16 tires, as they will likely make contact with more than just the fenders; they could hit the front and rear of the wheel wells in addition to the metal frame support that intrudes into the front well. And any modification of that piece is severely discouraged.

Yes, running something such as ET15 in a 15x8 wheel will prevent any type of spacing to fit any 225 tire. The Slipstreams are a rare enough wheel though, finding something ET15 that is both light and strong may be quite a challenge, and will only make the fender issue worse. I'm a fan of cheap universal 3mm spacers, they are thin enough that the wheel will still bear its weight on the hub and don't tend to seize as much as actual 57mm spacers.

For tires, I recommend the 225/50/15 R-S2 for 15" and both the 215/45/16 RT-615 and 225/45/16 R-S2. The T1-R is not a very capable tire, and clearly not in the same class as these two. I firmly believe that marketing has convinced the owners of this tire that it is the best ever made or something, but repeated track testing has shown that it is not a competitive entry at all.

Hope that helped.
Jay

[Van Westervelt]

The beautiful thing about 17's is that you have a lot of room on the inside due to the angle of the struts. This is why people with 17's and 18's can run 255's and other scary sizes, while people with 15's are stuck with 225's.

Now, your wheel specs are a little vague. Are the 17x7.5 and 17x8 wheels the same offset range as the 17x7 ET20-27 you mention? Let me know what your possible offset choices are, and I can tell you the optimal offset for each width. If you just want a general range, tell me.

Well when it comes to offset, I have several options with many spacers and custom spacers. My main concern is the tire that isnt stretched and can fit in the rolled but not pulled arches of a late model on IE3's.

[Mystikal]

Well when it comes to offset, I have several options with many spacers and custom spacers. My main concern is the tire that isnt stretched and can fit in the rolled but not pulled arches of a late model on IE3's.

In that case, aim for ET25 on the 17x7.5" and ET25 on the 17x8.0". No I didn't make a typo there, and the logic is correct; the 7.5" wide wheels will not rub with 215 tires at ET25, and will still fill out the fenders nicely. The 8.0" wheels stay at ET25 because that will give them a safe ~9mm from the front struts for any 235 tire, yet still fit within rolled fenders.

-Jay

[Jean]

Thanks Jay,

Looks like sport max 501 15x8 wheel is available in et15.

[Mystikal]

Yeah....no.

Stick with Slipstreams. :)

[Jean]

Where is the best place to order them ? I think I am going to get 15s for now. Does Rota make them in the right offset / size/pattern for e30s or will they need to be special ordered ? Thanks.

[Mystikal]

18racing.com is the sole supplier of the 15x8 and 16x8 ET20 Slipstreams, they were a custom run done just for the E30 (which I concidentally had a hand in designing; shamless plug). They were also made with 57.1mm hubs, so they literally are a custom run for our cars. There are VERY few wheels made today with both our offset and hub bore in spec.

And to answer your last question, yes they are a special order but I beleive they usually have a few sets in the warehouse.

[Jean]

Gotcha, so it's the choice between these two then (15X8 4x100 +20 57.1 or 16x8 4x100 +20 57.1 ) price difference between the two is almost nothing but then of course it will be offset by the price of the tires and understanding what wheel size with the same offset is best for a specific tire size.

Need to read through your other long thread to make sure this is best option for me, don't want to end up having to order spacers.

[Mystikal]

Search on here for what tires guys are getting away with on the 15" Rotas. If I had to guess one way, I'm be pretty sure the 225/50/15 R-S2 would be fine without spacers. It's mainly R-compounds that I'm concerned with.

The 16" wheels won't have any sort of issue on the inside, but yeah, tire prices do increase. Then again I prefer RT-615's to R-S2's (they are superior in most ways), so the 16" wheel is a very valid option.

[Jean]

If the 15" rotas won't have any issues with 225/50 R-S2 or RT-615s rubbing on the inside and on the fender lips (will roll the outside fender lips if I have to though) and I won't need any spacers I will go this route, just need someone to confirm this :)

[backtrail69]

The Rotas also clear BBKs well because of their design.