What speed rating is on your tires?

[FloydV]

Yes that is correct. Guys there is nothing to worry about with you tires.

It's not just having a Z on the tire. Z by itself indicates speeds up to 149 mph. If there is a W following in the string, then it is good to 168 mph. If the W has a parentheses around it, then it is good to speeds in excess of 168 mph. Actually there is a series of 3 characters (99W) would indicate in excess of 168 mph. What "in excess" means is anyone's guess. The numbers in the string (99W) don't have anything to do with the speed rating. The actual string on my Bridgestone tire is ZR17M/C(73W).

If there were a Z rated motorcycle tire that had a 99Y in the string then it would be tested to 186 mph. A parentheses around the (99Y) would indicate speeds in excess of 186. There aren't any DOT motorcycle tires with a Y or a (Y) rating that I can find. My guess is that this is true because there aren't that many bikes that can run these speeds.

Only an engineer could dream up a labeling scheme like this.

My guess is that exceeding 186 mph on (99W) tires for a short time is OK, but anything like 5 or 10 minutes, and you'd really be pushing your luck. I wonder how long (say on something like the autobahn) that a Busa could run 186 without burning up an engine. Maybe someone from Germany could chime in, realizing that 186 mph is equal to 300 kph.

 

[Blazing-Saddle]

I ran 170+ MPH for about 4 minutes on a set of ZR-rated Dunlop Sportmax tires back in 1992 and they blistered (the rear more than the front). I realize tire tech has come a long way since then but it still isn't wise to run too long over the speed rating of any tire.

 

[WWJD]

Yes that is correct. Guys there is nothing to worry about with you tires.

Agreed. From MOST engineers I know, they admit everything is UNDERSTATED as final specs for safety resaons. "This load bearing wall supports up to 300 lbs" mean the wall will hold 2 tons... that kind of thing. Protecting us from our own stupidity. It's really the best way to do it. Same reason our speedos are 15% off

 

[FloydV]

Agreed. From MOST engineers I know, they admit everything is UNDERSTATED as final specs for safety resaons. "This load bearing wall supports up to 300 lbs" mean the wall will hold 2 tons... that kind of thing. Protecting us from our own stupidity. It's really the best way to do it. Same reason our speedos are 15% off

That would have to be true for someone to run 256 mph and not blow a tire. There is a real scary pic of someone's back tire on the first page. Tires are also good for their rating for 2 years according to Zuke. I'm attaching a pic to show how to determine when your tires were made. Tires on sale might not be such a bargain if they are old.