2004 Slalom JCNA rules state that the 120 class (B) may substitute a radial tire of "equivalent" size to the 6:00 x 16" tires originally supplied. What is that size? 185 x 16" tires have commonly been used, but they are very expensive, there are only 2-3 makes available, and most of those are sold by Coker, etc., at prices varying from $175-200. per tire. The wear and quality of some of these tires is often questionable since they are made from old molds in limited quantities. A modern tire of equal height to the 185 x 16" is usually too wide for the XK rims. After shopping alot, I chose to equip my XK120 with 205/65R16" Kumho, passenger car tires. They cost $52.00/ea. plus shipping, have very good reports, a great ride, a wonderful warranty, and are a very close "equivalent size". They have a Tread Rating of 360 and are not "low profile", being only 1" or so lower in Dia. than the 6:00 x 16" bias-ply tires they replaced. In fact, my 120 sits only 1/2" lower on the Kumhos which is well within the adjustable range of the suspension as permitted in the stock class by Rule 1.G. There is NO better modern, affordable, radial passenger tire available for my XK120 on stock rims. A 120-140 should be allowed to run in Class B with these tires.
