BMW E30

The important question, for which we could not find the answer on any BMW website, is what size wheels are the best for BMW E30 325i because it is hard to find 4-lug rims with the right offset.
For those who want to use 17" rims (street use), we would recommend the offset 28.20mm with tires 215/40/17, but not many tire manufacturers have this size. If you are going to use 17" rims for BMW E30 325, you definitely need to install performance shorter springs, otherwise your BMW will lose its style and the clearance would be too high off the ground.
We recommend 15" rims for race track and autocross because there is a big selection of racing tires (225/50/15 and 225/45/15): Hoosier, Kumo V700, Yakohama, etc. If you find stock BMW BBS rims for the 325ix with an offset 41, 20mm spacers can be used to get the right 21mm offset. There is another popular set of aftermarket BMW rims 15x7 or 15x8 made by Kosei with an offset 20mm that you can purchase at Tirerack.

On 15x8 rims we used Kumo V700 tires 205/50/15 that fit very well on BMW E30 325, but if Hoosier tires 225/45/15 are used, smaller offset may be needed on the front axle because the clearance between the rim and the strut is very small and you might need to use about 5mm spacers.
The compatibility of the wheels with BMW E30 depends on the way your BMW suspension is set (the clearance between the rear fender and the tire, how much it is lowered, and condition and material of bushings)
When the clearance between the rear fender and the tire is too small, you may need to trim or bend the inside if the BMW E30 fender in order to avoid contact.
We think that tires with an overall diameter of 24" or more do not enhance the look of BMW E30 and decrease performance.

BMW performance Koni Shocks

For over fifty years of experience, Koni has earned themselves a worldwide reputation for quality and reliability.
Our experience has shown that BMW Koni Shocks are the best performance shocks on the BMW performance parts market if you want to enhance the performance of your BMW suspension.
If you decided to improve your race cars BMW suspension, the first and most important step would be choose the right performance shocks for your BMW car. Shocks from manufacturers such as Boge and Sachs do not increase performance of your BMW, but are considered a good replacement for your blown out BMW stock shocks. Our experience with KYB shocks has shown that they do not enhance the handling and show worse performance than stock BMW shock.
If you are serious about getting into the car racing world, you would need to use quite expensive systems (we are talking about thousands of dollars) such as Moton, JRZ, modified Koni or Bilstein shocks which can be purchased from Tuner Motorsport and Ground Control.
With a racing suspension, a bmw becomes unsuitable for everyday street driving, but not everyone can afford to have a truck with a trailer to take BMW to the racing events. That is why we work with BMW customers that love to drive their BMW everyday and enjoy it, have fun while driving, feeling themselves behind the wheel of a sports car, and participating in different racing events whether it is autocross, rally or track racing. For that kind of a BMW driver there are only two choices: Koni or Bilstein.
What is the difference between two world class leaders? BMW Koni Shocks are adjustable, which allows the BMW driver to adjust the suspension to any driving style and to the different spring rates of various manufacturers. These characteristics make Koni for BMW more popular among the lovers of aggressive driving than any other performance shocks available on the BMW performance parts market.

BMW performance Hawk brake pads.

BMW genuine brake pads are excellent for street driving, autocross, and Rally cross. The stopping power they provide is better than any after market brake pads, except Hawk HP plus. Hawk HP plus performance brake pads show extremely high friction output, but there is a downside to it such as brake dust, noise, rotor wear and brake life.
Front brakes require more attention than rear because most stopping power comes from the front. On the race track you need to use performance race compound brake pads. From our experience we believe that Pagid Orange Hawk Blue stuff brake pads are to be the best performance brake pads for race track.
We would not recommend buying after market brake pads.
Performance steel metal brake hoses do not make a major difference in your braking system, except when you are on the race track. Also we would not recommend using special racing brake fluid (ATE Blue) because, from our experience, we noticed squeaking noise from clutch master cylinder.
Do not forget to change the brake fluid once every two years.

BMW performance H&R product.

This German company can be trusted 100 percent. Any BMW performance product that we have installed fits as well as the original BMW parts. Although there are some questions such as installed rear springs lowered the car by more than 1.3" (H&R specification), but this can be corrected by installing a spacer under the rear spring to achieve desired clearance for the rear tires. On BMW E30, we might consider Eibach springs for autocross because they work best in the small radius turns, but H&R are excellent for big radius turns, when with Eibach your BMW may loose traction.
You feel a lot safer with BMW performance H&R Springs because they eliminate over steer. BMW H&R Springs work great on BMW E36 and BMW E46.
Eibach and H&R are two leaders in the field of performance suspension technology, that is why most of BMW tuners prefer their products.