Ronal paint codes/colors

[Frederick Smith]

Just a data point. 225/50/15 on Fuchs require no fender lip mods and
do not rub at any point on the body or the chassis. The tires are
RE71's.
The speedo error is 3% as compared to the 205/60x15 @ 75mph, 225/50 =
72mph.
diameter diff 205/60 vs 225/50 -.415in.There is roughly .790 increase in
width, .395" inside and outside.

How do I know??????? 
http://www.venommotorsports.com/howto/wheeldiameters.htm

Smitty