We are building a streamliner and due to the configuration, can only obtain height above the salt by using taller tires. I need tires that are at least 30' in diameter with a speed rating of 186 or faster. I have searched without success. Any suggestions? help! Please reply to my email photio@aol.com.
Thanks.
Walt
You are looking at street tire catalogs, not the SCTA rulebook, or racing tires.
Y rating is 186mph
(Y) rating is 186++ mph.
This has nothing to do with SCTA tire rules. The SCTA currently does not acknowledge the (Y) tire exists. These are what you find on OEM cars that have top speeds in excess of 200mph.
You are allowed to go up to 200mph with VR (very obsolete designation) and ZR tires (in the process of becoming obsolete, it is a meaningless designator today).
A V-rated tire is a 149 mph tire. A ZR-rated tire is a >149 mph tire. Today tires are rated by load and speed:
A 120V mean it will handle a load of 3086lb (120) at 149 mph. There is no such thing as a 120Z, Z is no longer a speed rating. It is a throwback to a time when nobody thought a production car would go past 150mph. There is no VR at all today.
All the 30"+ speed rated tires come off of high performance pickups or SUV's. The largest I could find is a 32.4" Toyo that is 120V. I tested these at 215 mph at Standard Testing Labs, and after 20 minutes at 2200lb load, a small chunk of tread flew off, so I decided not to risk it. HOWEVER, the (Y) rated tire I tested at 215mph and 2200lb (overloaded) exploded before it got up to 215, IIRC, it blew at 210?
So the load rating is actually more important than the speed rating. An overloaded tire will seldom survive even at less than it's rated speed.
SCTA LSR tends to frown on street tires. They tend to be very wide, which can induce a spin. While I found my truck to be MORE stable with treaded wide street tires, my truck is heavier than most entries, usually about 7000lb in LSR mode.
If you want to avoid hassles, go with the 30-18 Mickey Thompson Bonneville's. Those get no questions in tech. Anything else can possibly cause a ruckus.