scorciae

how important are those tire numbers, i think i have the Ps on mine which are like 100mph, but i have done much more for sustained periods. is this dangerous, has anyone ever had a tire blow or melt or whatever they do at that speed?

gkull

When the pavement is cold, your tire pressure right, and your not near the tire rated weight limit. Your fine.

Years ago i was heading home on the freeway and way up along the road I saw that a car was off the road. As i got closer it was Vette. So i slowed and pulled over.

This guy had a hot 69 with something like N50's on the rear and he told me that he was driving about 100mph when he had a rear blow out. It scared me! :sad: The rubber whipping around had torn off the body or should i say the whole rear quarter panel clear up to the window post. It wasn't a $100 blow it was $2000.

SanDiegoPaul

I worked in the tire business for almost ten years ... and I've seen it all! I recommend tires in the right performance range for your driving. You need to remember that not only is the proper SPEED rating important but that also directly affects the PERFORMANCE of the rubber.

You want complete control at high speed - not partial! And the proper sidewall stiffness is what accomplishes that especially on a heavy car. I HATE the way my car corners at speed with the Firestone SS20 Indy tires. I bought them for appearance but am really thinking about an H rated tire to replace them with. I'd love to find a buyer for these things! (225/70r15)

aharte

I was once in a friend's mercedes when he was driving 110-115. After a few minutes, we smelt something burning. I suspected the tires, so we got off the highway and checked. They were rated to 106. Apparently, there's not much leeway. Its not worth risking it.

Ganey

Exactly. Where there are no speed limits in Europe, it is said that if one gets stopped the first thing they check is the tire speed rating- if in excess of the tire speed rating- ticket.

Some ex. Blew bias ply ft. tire in excess of 100 cruise in non Vette. No problem. The stock rear radial of the Corvette started separating on the way (fast accel., maybe 90) to 100+ cruise. No problem.

Gary79

i have BFG Ta's, rated 112 mph. anyway before i bought them i asked a few questions, the rating limit, in this case 112 mph is about the speed where the tire starts to crown, in other words the center of the tire is the only part making good contact with the road. you're okay as long as you're going in a straight line. to me it's not worth the risk.

zwede

Every now and then I take my vette on roadcourses (non-competitive, just for fun), and I really didn't feel comfortable on a roadcourse with tires rates for 112 mph (S-rating).

Now running Z-rated 17".

The Money Pit

Did 113mph once,and it was OK.Maybe next time I'll go for 114mph!
There's got to be some margin built into the ratings. The question is what is the fudge factor,and are you willing to risk it.Think about your 12vdc headlights that burn for years with a charging voltage of 14.7vdc.
The main difference I've noticed is the sidewall stiffness on the higher speed rated tires. If you're into the twist and shout thing,don't skimp on the tires!

Vetterodder

Running a tire for substained periods at speeds beyond what it's rated for is a very bad idea. The problem is heat build up in the tire. A quick burst up to high speed won't cause the tire to overheat (unless there's a problem with the tire to begin with) but the longer you run it at high speed the hotter it gets. Rules at the drag strip can be very finicky about helmets, roll bars, driveshaft loops, etc. but they don't give a hoot about your tires speed rating because they know it'll only be running high speed for a few seconds.

The heat is due mostly to tire flexing as it rotates with a load on it and the faster it rotates the faster the heat builds. Typically, higher speed tires will have a stiffer sidewall that flexes less and will also be constructed to handle higher heat without failing. Keep in mind that the speed rating is VERY dependent upon the tire being properly inflated. The safe limit of an underinflated Z rated tire might actually be lower than that of a properly inflated S rated tire. Personally, I prefer higher speed rated tires on most of my cars because, of their intended use, they tend to be designed for better performance also.

Having been in the business also, I've seen plenty of failed tires. The most common cause was underinflation, followed by sidewall damage and tread separation. The tire might hold together just fine until it was subjected to substained high speeds.

HcDave1

what kind of tires do they put on extreem sports cars? such as fararri, L. diablos cars that are said to hit 203?