I came across this interesting explanation of tire speed ratings. Of interest is the Z rating. When Z-speed rated tires were first introduced, they were thought to reflect the highest tire speed rating that would ever be required, in excess of 149 mph. While Z-speed rated tires are capable of speeds in excess of 149 mph, how far above 149 mph was not identified. That ultimately caused the automotive industry to add W and Y speed ratings to identify the tires that meet the needs of new vehicle, like our Hemi Challengers, that have extremely high top speed capabilities. W=168 mph Y= 186 mph
(Y) is 186mph and faster. Many of the Michelins are thus rated while lesser tires are merely rated TO 186, which is a Y rating. But, do your research on tires, and you will find some are not as good as their actual rating. Why get tires rated for the speeds your car can go? Because you never know when/if you may find a need to top out to save your life or the life of someone else. Why not be on the safe side?
No, my Nitto Motivos had a high mileage rating, but were too hard and lacking in traction. They had a Y rating, which is good, as I had them over 170mph more than once, but, oy vey, they could not compare to the Mickey Thompsons in grip, which wore faster but were only W-rated.
To what are you referring? I have had the Hellcat over 170mph on several occasions. 180 was my top speed so far. I don't think it's entirely unusual, for me, anyway. However, some have never been within 50 or 60mph of their car's top speed, and that's fine for them. I was trying to top out but ran out of room and had to slow down. It is one reason I actually made sure to get Y rated tires. I didn't want any doubts or lack of structural integrity at speed. Not all of us just buy cars to look nice in. Some of us buy them to do with them what they are designed to do. For others, they don't even need V rated tires. In fact, many don't even need a working car.
I don't know the exact length of the road. It sure wasn't the odometer that I was looking at. But it was wide, straight, and close to perfectly suited to the task, as far as engineering went. I just wished it was longer before it was interrupted by a change in direction, because I was trying to hit 200. If you want to get to the top speed of a lower-powered car, you will need a very, very long road indeed. A 485hp car would theoretically be limited to 176mph, THEORETICALLY, IF the same car could do 200 on 700hp. However, after that car hit, for example, 156mph, it would take 337 of its hp just to fight off overall drag. This only leaves 147hp to accelerate for the 485hp car, but 332hp left to accelerate the 700hp car, or, over double the rate of acceleration. This ratio/gap increases with every mph added, ending up with the lower-powered car having nothing at all with which to accelerate. As the 700hp car passes 176mph, the lesser car's top speed, it still has 215 left to continue acceleration. Near top speed, it can take miles and miles of road to eke out the last few mph because so few hp remain that aren't being consumed by overall drag. At 180mph, 20mph short of the STATED top speed of the Hellcat, The overall drag is consuming all but 190 of those 700hp. 186: 138hp left 190: only 44hp left to accelerate a car that has an overall weight of 4200 pounds or whatever these things are As one approaches one's top speed, the last few mph get ever-more-difficult to find. However, the greater the car's power-to-weight ratio, the more quickly it can get close to its top speed. If the car weighed NOTHING, then the top, overall-drag-limited speed would simply be almost instantly achieved, squashing the driver with the g-forces before hitting the wall of speed versus hp, and suddenly acceleration would be ZERO at which point the driver would be pushed hard against his seatbelt by his seat bouncing him forward, if he survived the acceleration to top speed. It is rare for people to try to wind their car out to top speed, I have noticed. For most cars, the amount of power available to accelerate the car for the last few mph means they would have to have something long, straight, and flat to (kind of) safely approach their top speed. But, with over 700hp, can the Hellcat get to 180 faster than it would take a 485 hp car to get to 150? I don't know. I think it would take less road, though.
