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Discussion Starter · #1 ·
How to Measure Wheel to Fender Gap for Wheel Spacers - DIY with Pics

Disclaimer: I am not a BMW technician. This article is provided freely for entertainment purposes only and does not come with any warranty. Use the information in this article entirely at your own risk.

This DIY demonstrates a fast method of measuring tire-to-fender gap which can be used to help determine what size of spacer can be used on your car without causing tires to rub. This DIY does not cover how to install spacers or the pros and cons of using spacers.

A. Background on Spacers:

Wheel spacers are used to address several wheel fitment issues but the most common application is for aesthetics - spacers can give your car a wider more aggressive look by pushing the wheels out resulting in a better stance. The farther you push the wheel the better the look, so people tend to want the widest spacer they can fit without causing the tire to rub on the fender.

This leads to a very commonly asked question on the forums: what size spacers should I buy?

There is no perfect answer to this question due to the differences in wheel offset, ride height and maximum tire width which all vary from car to car. Other than test-fitting several different sets of spacers, the best way to determine which spacers will work is to measure the tire-to-fender gap on your car.

B. Supplies needed:

  • Tape measure or ruler with millimeters (spaces are sold in metric sizes)
  • Masking tape
  • 12" of lightweight string (sewing thread, dental floss or kite string are ideal)
  • Large washer or other weight for the string

Here is a diagram from H&R which shows what we are measuring

Personally I do not like using the ruler method suggested in this drawing as it can be skewed by negative camber and the thickness of the ruler/straightedge used on the wheel.

C. Tire Gap Measurement:

1. Tie Weight to String
Attach a weight to one end of the string. I used a large washer but anything will do, even a large screw will work.

2. Tape String to Inner Fender
Use masking tape to attach the string to the inside of the fender. It is a good idea to clean the area to be taped with a rag to ensure good adhesion. Make sure the string is flush with the inner lip of the fender.

3. Measure Distance from Widest Point of Tire to String
In the example photo I placed the tape against the wheel lip since the tire is slightly stretched on the wheel. If your tires are wider than the rim (which is the case for 6 series OEM rear runflats) then place the tape on the widest part of the tire sidewall.

Measure the distance from the wheel to the string. Order spacers that are slightly less than this measurement.


3,646 Posts
Discussion Starter · #5 ·
Fronts are rears will be different, with more room in the back where you can typically install lager spacers.
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