Speed rating of tyres

seatbeltnoob

I think the tyre speed rating are used more for the attributes of the tyre compound rather than the speed itself. Tyres rated at higher speeds are likely to have better flex.

Look at the slow mo of the drag racing tyres: https://youtu.be/rw3LE78gwhg?t=21s

The recommended speed rating goes up as you use lower profile. Which suggests to me that the thinner sidewall (profile) needs to be even more flexible in order to compensate for less material available.

BeenThroughItAll

seatbeltnoob wrote: »

I think the tyre speed rating are used more for the attributes of the tyre compound rather than the speed itself. Tyres rated at higher speeds are likely to have better flex.

Look at the slow mo of the drag racing tyres: https://youtu.be/rw3LE78gwhg?t=21s

The recommended speed rating goes up as you use lower profile. Which suggests to me that the thinner sidewall (profile) needs to be even more flexible in order to compensate for less material available.

Well, you'd be wrong. Lower profile tyres are almost always significantly stiffer than higher profile tyres. Plus, you can buy higher profile tyres in higher speed ratings. An example - 205/50/15, with a V (149MPH) rating, or 205/50/16 with a W (168MPH) rating - neither are exactly 'low profile' with a 10.25 cm sidewall.

seatbeltnoob

BeenThroughItAll wrote: »

Well, you'd be wrong. Lower profile tyres are almost always significantly stiffer than higher profile tyres. Plus, you can buy higher profile tyres in higher speed ratings. An example - 205/50/15, with a V (149MPH) rating, or 205/50/16 with a W (168MPH) rating - neither are exactly 'low profile' with a 10.25 cm sidewall.

I'm talking about flexibility of the material, not tyre. I.e. per cubic cm of material from a low profile tyre to that of a high profile tyre.

The profile of the tyre is exactly the same in your example they're both 50% of 205.

Yes you can buy tyres in all sorts of speed ratings, but I'm talking about different tyre profiles on the same car where the manufacturer as specified different speed ratings for different profiles.

Gosh you love to argue for the sake of arguing.