So, in 1:1 scale, an advertised 19" x 10" wheel is ACTUALLY 20" x 11", as they do NOT count the bead lip (either height or width) as a measurement when calculating/advertising wheel size. If 25.4mm = 1" (which it does), then take the guys rim dimensions and divide by 25.4 to convert to inches and then divide that by the scale you want them to go under to get scaled rim dimensions. so, in 1/25th scale, the fronts/rears are: F 26.61" x 9.85" R 29.53" x 12.8" in 1/24th scale, the front/rears are: F24.58" x 9.45" R 28.34" x 12.29"