The RD35 has a cold durometer of 52-54 and is designed
for dry tracks that are dusty, sandy, loose and lack grip. The D40A
will have a cold durometer between 55-57 and is designed for medium
hard tracks that have little moisture and begin to form a
Contact your nearest Hoosier Racing Tire distributor
or dealer for purchase or visit www.hoosiertire.com
for more information.