Tech Forum : Wheels

davethedog

Posted Sunday, Aug 5th 6:44pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 178

Northants, England
E21 320

I have just sold my 14" schimt wheels. I am looking for something for sutible for racing.
What do you guys think would be the ultimate wheel / tire size for the E21.
Also can anybody recommend a good quality race wheel in this size.
I am considering buying a set of Jason's wheela arch's so please consider this as an option.

Boost_me

Posted Wednesday, Aug 8th 3:10pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 286

Victoria, Australia
1981 BMW 323i

When I had my e21 I fell in love with these wheel's......

Their 'WRD Chevlon DE Mesh'.......I think they'd look sexy on any e21.....I would use either 15's or 16x7in in front and 15-16x8-9 in rear(I heard a roumor 10inch wide will fit stock guards with maybe alip and a roll).....And e21 have a very low offset from factory which makes it harder......I would choose these diamiter's for tire choices compared to smaller wheel's, If you wanted to you could push for 17's.....but for racing I wouldn't.....15-16.....

M42powered

Posted Wednesday, Aug 8th 5:50pm [Edit] [Quote] [IMS] [View car]

Staff
Post nr. 725

Arizona, USA
1981 BMW 320i

Depending on your brake sizes, or need to upgrade to a larger rotor. I would stick with a 14" wheel. Big wheels are just for big brakes on heavy cars. The smaller the rotors and calipers and wheels the less unsprung weight you have.

I have wanted to take a set of stock Steel wheels and have them widened for quite sometime. But for racing these might be a little heavy. The only way to go is with a modular wheel. It's exspencive but if you want to fill those wheel wells with as much rubber as possible you're going to need to have the ability to put lips and barrells on a center hubs.

What racing are you referring to? Are there classes? Tire restrictions? DOT tires? Give us the details.

davethedog

Posted Friday, Aug 10th 3:32pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 179

Northants, England
E21 320

M42powered wrote:

I am looking at entering the Time Attack championship. I am desperate to race but, as I am truly under the thumb my wife dos'nt like the idea. So this seems a good compromise. You are on your own on a track with one flying lap to set your time. There are very few restictions on modifications and wheels are free, but the tires must be road legal.
When my Dad was racing his E21 in the BMWRDC he only ever used 7 x 15's as this was the limit set by the championship. His car would out handle ANY M3 so I was thinking along these lines. Possible 7 x 15 on the front and 8 x 15's on the back. I really like these wheels.

http://www.comp.co.uk/wheels/popup.asp?wheel=58

I think they would look smart and be a good strong lightweight wheel.

I was looking at using Kumho tires as these have been extensivly used on BMW's and proven to be good as they are the control tire for the BMWRDC.

Opinions please people

KenDanielson

Posted Saturday, Aug 11th 9:54pm [Edit] [Quote] [IMS] [View car]

Junior Member
Post nr. 192

Petaluma CA
'82 320is, '78 320i

I just spent some time under my '82 taking measurements with a 15x7 et12 wheel (tire removed) on the rear hub.

There is .5" clearance from the wheel to the trailing arm so you can't go much wider inside unless you go to a larger dia. wheel. With a 16" dia. wheel you gain another .5" to the trailing arm because it slants towards the center of the car slightly as it goes fwd. This does NOT address clearance between the tire and the shock body/spring.

There is about .5" from the outer lip of the wheel to the inner edge of an unmodified wheel arch.

I am considering going to a 15x8 or 16x8 et0 wheel with a 225 wide tire, the inner backspacing is within a couple mm of the 15x7 et12 so that's not a problem. The extra 25.4mm of width is all on the outboard side-that WILL present a problem requiring the wheel arches to be bulged some. I'm not afraid of custom bodywork. Here's a pic of the Sport Max 002 wheel, click the pic for larger version.

They also make a 16x8 et15 wheel in a different design that should fit also. Here's a pic of that one.

In 15x8 et15 that one would be pretty darn close to the trailing arm.

Tire choice has a lot to do with clearance also, some mfgs use a more square shoulder than others in the same size. The square shoulder can fill up space more than a tire with a more rounded shoulder.

ken

Tricord

Posted Saturday, Aug 11th 11:01pm [Edit] [Quote] [IMS] [View car]

Administrator
Post nr. 1013

Belgium, Europe
323i Baur

I race with 15x7 rims fitted with (currently) 225 wide Dunlop slicks. This config is better than my current Alpina B6 suspension, I still have too much rolling in tight corners. In ideal circumstances, I would have to upgrade the suspension to match with the wheels and tyres.

However, to give an idea on the actual cornering limit of my car: it's currently not the wheels, not the suspension, not the rolling... It's the engine! When cornering tight in longer turns, my engine starves on oil, despite having the oil level topped up over the max limit!

jesse

Posted Monday, Aug 13th 7:00pm [Edit] [Quote] [IMS] [View car]

Member
Post nr. 361

SF, USA
Dinan 1978 333i, honda insight, audi S4

dry sump here you come!

all you needed was a good enough excuse right?

M42powered

Posted Tuesday, Aug 14th 10:42pm [Edit] [Quote] [IMS] [View car]

Staff
Post nr. 726

Arizona, USA
1981 BMW 320i

A decent oilpan baffle might do the trick.