Frequently Asked Questions What size wheels are required? Are spacers required for wheel clearance? What about caliper piston dust boots?  Are these required? What size wheels are required?  back to top Descriptions below are basic recommendations, but always check the wheel fitment diagram for your application. E46 3-series '99-'05 330, 328, 325, 323 Minimum 17" x 7.5", standard offset.  Some original wheels may require 5mm-12mm spacers. E36 3-series '92-'99 M3, 328, 325, 323, 328 E46 M3 Minimum 18" x 8", standard offset. Some original wheels may require 5mm-12mm spacers. E90/E92 3-series, 348mm front kits E90/E92 3-series / M3 380mm Mega front kits Minimum 19" x 8", standard offset. Some original wheels may require 5mm-12mm spacers. E90/E92 3-series / M3 380mm Mega front kits E60/E92 3-series / M5 380mm Mega front kits Wheel fitment guides for 3-series/M3/Z3/Z4 (click to download .pdf file): E36/E46 front 4-piston/325mm rotor Are spacers required for wheel clearance?  back to top 17" and larger original BMW wheels may need spacers, and many aftermarket wheels we have test-fitted also fit without spacers. Most aftermarket wheels have more clearance than original BMW wheels but some styles may still need spacers.  It is very important to use the fitment guides linked above, print out to life-size and fit within your wheels to ensure clearance.  What about caliper piston dust boots?  Are these required?  back to top Each piston has an internal pressure seal and dust seal. These ultra-resilient seals minimize piston retraction so that pedal travel is short, consistent and they are resistant to knock-back. Since they are internal to the caliper, they are shielded from the hi-heat that prematurely shortens the life of competitors caliper seals.  Installation  back to top Installation is a very straight-forward "bolt on" and can be performed by any competent automotive technician following our simple installation guide.  Minor trimming of the heat shields is required, and rear kits may require grinding off a small piece of non-structural excess casting flash on the spindle. You can download the installation guides on the respective pages for each application, please see link on previous page.  Uses Adobe Acrobat .pdf format- download free Adobe reader, click here: