Quote:
Originally Posted by cmb570
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You mentioned an option of installing H&R lowering springs which are typically much stiffer than stock and 1.5" drop. Recommend checking for other options to consider such as if say Eibach or Dinan have a moderate drop spring (~3/4") that is a little more stiff than stock but not as stiff as H&R.
Also another way to eliminate some fender gap is to upgrade tires and size. For instance if I upgrade stock Pirelli runflats in 225/45-18 to summer Michelin goflats in 245/45-18, it would provide better handing and slightly higher sidewall for better comfort over poor roads which also would fill gender gap. Remember NOT to use sizes on sidewall to calculate sidewall height. Those online calculators are all inaccurate for the same reason. Use the TireRack website to look up the ACTUAL measured diameter of a particular brand/model and size of your stock tire to a proposed tire to calculate exactly what the sidewall difference might be.
Remember that a 1" drop in springs will eliminate 1" of fender gap. But a 1" difference in tire diameter will mean a 1/2" of fender gap eliminated. (It's the difference in the radius of the tire which is the amount above the wheel center or hub.)
You should be able to make measurements of your current fender gap and know exactly how that gap will change before you spend a dime on springs or tires.
To get exact measurements I use the following:
Painters/masking tape
Thin straight edge
A level
An inexpensive measuring caliper (Harbor Freight)
Tape measure or ruler
1) place painter's tape on fender lip at peak.
2) use level vertically to place a pencil mark on the tape directly above the centerpoint of the BMW logo on the center of the road wheel
3) use caliper to measure distance from top of wheel to fender lip at the pencil mark. Write down that number.
4) place thin straight edge across the top of the tire sticking out of the fender at the pencil mark. Use caliper to measure distance from the straight edge on top of the tire to the bottom of the fender lip at the pencil mark.
5) use tape measure or ruler to measure the distance from the centerpoint of the BMW logo on the road wheel to the outer edge of the road wheel.
With those measurements, along with the spring manufacture's drop predictions and TireRack's measured tire diameters, you have everything that you need to know what your current wheel gap iis and be able to predict accurately any change in wheel gap if you changes springs and/or tires.
Hope this helps!