Running 17" wheels in F-Street?

[mmilkov]

I have a 2008 135i and I am thinking of taking advantage of the change in the autocross stock class rules and going from 18" to 17" wheels. Has anyone tried that? My thinking is that by keeping the same aspect ratio tires, I will effectively lower the car by 0.5". The tires I might put on are 245/40ZR17 in the front and 255/40ZR17 in the rear. Will these fit? I know the rears will, but I am not sure about the fronts.

[timbo_3101]

One of the 1ers here races with 245/40/17 up front, so this should not be an issue.

[mmilkov]

Originally Posted by timbo_3101

One of the 1ers here races with 245/40/17 up front, so this should not be an issue.

Is he running a 17x8 or 17x8.5 in front? What offset?

[Jazzy]

What are these rule changes? I tried looking on the SCCA site, but couldn't find anything.

[mmilkov]

Originally Posted by Jazzy

What are these rule changes? I tried looking on the SCCA site, but couldn't find anything.

You can look here:
http://scca.cdn.racersites.com/prod/...-june-solo.pdf

The changes in rules between Stock and Street can be found in the June Fastrack, but they're mostly the same, with the following two key differences:

±1" diameter (from stock) wheels may be used. You must still use the same width as stock, and the offset rules are the same.

There's an allowance to "defeat" any traction control or stability systems that don't come with a factory method of disabling them.

There was some talk about allowing camber plates in the new SCCA stock/street class, but, alas, it did not get accepted.

Also, what sucks for us, is that pretty much all 1 and 3 series BMWs fall into F-stock. This includes the E46 and E90 M3's.
http://scca.cdn.racersites.com/prod/...k-aug-solo.pdf

So how am I supposed to be fighting the M3's with a 135i?

[Ginger_Extract]

Unless the stock class rules have changed immensely since my last perusal through the rule book, you can't change wheel widths, only offset +/- .25", OEM 135i wheels are 7.5"F, 8.5"R....

[mmilkov]

Originally Posted by Ginger_Extract

Unless the stock class rules have changed immensely since my last perusal through the rule book, you can't change wheel widths, only offset +/- .25", OEM 135i wheels are 7.5"F, 8.5"R....

Quite true. But now you can change wheel diameter plus or minus 1".

[Ginger_Extract]

Unfortunately, you're pretty much stuck with the 225/255 stagger. I know that some AutoX'ers will pinch a 255 square setup on the 7.5"/8.5" wheels, but it's not really an effective solution. So, it's a judgement call.

[mmilkov]

Originally Posted by Ginger_Extract

Unfortunately, you're pretty much stuck with the 225/255 stagger. I know that some AutoX'ers will pinch a 255 square setup on the 7.5"/8.5" wheels, but it's not really an effective solution. So, it's a judgement call.

I am fine with 255/35-18 in the rear.
I know that 225/40-18 fits in the front, but I might be able to fit a 235/40-18. This size is available with RS2's and Z2's.

If I go with 17 wheels, then in the front I can try to fit a 235/40-17 (available for Z2 only) or 245/40-17. Compared to 18" wheels, I benefit from 0.5" reduction in radius and less chance of rubbing against the fenders. The rear can be 255/40-17.

[Lubo]

Originally Posted by mmilkov

I am fine with 255/35-18 in the rear.
I know that 225/40-18 fits in the front, but I might be able to fit a 235/40-18. This size is available with RS2's and Z2's.

If I go with 17 wheels, then in the front I can try to fit a 235/40-17 (available for Z2 only) or 245/40-17. Compared to 18" wheels, I benefit from 0.5" reduction in radius and less chance of rubbing against the fenders. The rear can be 255/40-17.

Your 1er is still fairly heavy car even though its size suggest otherwise. Add the lack of camber soft springs and loss of camber under cornering and you will be rolling over the tires like a mad man. Pinching a tire will only exaggerate this roll over not to mention that it will make the tires a lot more sloppy and slower to respond to the steering wheel input. In my opinion if you will run 7.5" wheel you should stick with 225 as max tire width.

[Simmons-Racing]

Does anyone make the right offset and width for stock class?


Simmons

[PrematureApex]

Front alloy wheels: 18x7.5" ET49


Rear alloy wheels: 18x8.5" ET52


He can run 235s on a 7.5" wheel. 235/45 17" works without rubbing. 235/40 17" of course, but tires are more limited.

235/40 on 7.5" was OE E36 M3 in 95 wasn't it?

People have run 235/40 18s on stock wheels as well without issue...

Using up the .25" offset allowance, he may be able to run 245s and be OK. Would depend on who yo ask if it's effective, but most avid autoxers wouldn't call a 245 on 7.5 overkill...

I'd certainly give a stiff 245/40 17 a go.

OP, you get about 6mm of slack. So a 43 offset is the lowest you could run.

Honestly, I'd start with an ebay search for BMW wheels, select 5x120, 17", 7.5", and all the offsets between 43 and 50. See what wheels are out there, both used stock and some aftermarket.

Some 17" OEM 1 series wheels are 7.5" with a 47mm. They also made a 47 offset style 68 wheel.

[PrematureApex]

Are you allowed to use spacers if you stay within the wheel offset limitations?

Like run a 50mm wheel with a 5 mm spacer?

[Kgolf31]

Originally Posted by PrematureApex

Are you allowed to use spacers if you stay within the wheel offset limitations?

Like run a 50mm wheel with a 5 mm spacer?

Yes, you are.

OP - 17s will effectively lower weight, and help on tire costs.

Keeping the same aspect ratios, will help increase acceleration. Make sure you don't shorten 2nd gear too much...that would be my only concern.


Is the 135 really in FS? I find that hard to believe. I thought they were in DS along with the Boost Buggie.

[Simmons-Racing]

Originally Posted by Kgolf31

Yes, you are.

OP - 17s will effectively lower weight, and help on tire costs.

Keeping the same aspect ratios, will help increase acceleration. Make sure you don't shorten 2nd gear too much...that would be my only concern.


Is the 135 really in FS? I find that hard to believe. I thought they were in DS along with the Boost Buggie.

They are in DS on R-comps, and in FS with street tires.

I think 17's make sense also, just didn't know what wheels were available.

Hopefully buying a 2010 135i this week

Simmons

[Simmons-Racing]

Does anyone make a 17x7.5 42mm and a 18x8.5 45mm in the same wheel?


Simmons

[Ginger_Extract]

Actually, if you want to use Stock class rules, look for a set of style-68 wheels from an E46 330i sport package. 17x7.5 ET4x (45ish?) in the front, 17x8.5 ET50 in the rear. It's a direct bolt-on 17 inch fitment that effectively mirrors the stock style 264/261 wheels of the 135i, albeit in lighter, less expensive, 17-inch form.
If you're interested, hop on eBay, BimmerForums, and E46Fanatics. They seem to pop up frequently.

[Simmons-Racing]

Originally Posted by Ginger_Extract

Actually, if you want to use Stock class rules, look for a set of style-68 wheels from an E46 330i sport package. 17x7.5 ET4x (45ish?) in the front, 17x8.5 ET50 in the rear. It's a direct bolt-on 17 inch fitment that effectively mirrors the stock style 264/261 wheels of the 135i, albeit in lighter, less expensive, 17-inch form.
If you're interested, hop on eBay, BimmerForums, and E46Fanatics. They seem to pop up frequently.

I looked them up, and they are showing 41mm offset for the 7.5 ?


Simmons

[Simmons-Racing]

Do you think the car has a better chance in F-street or STU?


Simmons

[Kgolf31]

Originally Posted by Simmons-Racing

Do you think the car has a better chance in F-street or STU?


Simmons

I have to look up the competition for what F-Street has to offer, but IMO nothing can compete with the Boost Buggies in STU right now.

A E36 M did win Nationals in 2012, but IMO that course was set-up to give boost buggies hell...

The 135s just can't fit enough tire under the car to make them grip in STU.

[Ginger_Extract]

Yup, I'm running STU locally, and getting DESTROYED by everyone. It seems that the three fast regulars in STU here have an E36M3, STi, and an Evo VIII. They have less weight, more limited slip, better suspensions, and as much, if not more tire than my 1'er.

[Simmons-Racing]

Do Corvette wheels fit the 135?

Simmons