What are the differences between speed rated tires?

[Shel_B]

Are there differences in construction, weight, sidewall strength or stiffness, and maybe even tread pattern depending on the speed rating of a tire? Ex: are tires rated for higher speed heavier or lighter than lower-rated tires? Is their tread deeper or more shallow? What other differences might there be?

 

[Jetronic]

The difference is in the belts mostly, though some tyres seem to use a softer compound for higher speed rated tyres

 

[CapriRacer]

The only sure difference is the amount of cap plies - the higher the speed rating, the more cap plies. Nothing else is required.

HOWEVER, the tendency is for higher speed rated tires to use grippier, but more rapid wearing tread compound, less tread depth, with a stiffer, harsher riding, but quicker responding sidewall.

 

[twouvakind]

Price.

 

[userfriendly]

With E rated truck tires, the tread depth and total weight of the tire in addition to cap plies and construction changes the speed rating.
For example my 295/65/20 Toyo CTs weigh over 70 Lbs, have a 18.4/32" tread and a "Q" speed rating.
Other examples of the same size may have a "R" or "S" speed rating.

 

[351FUN]

Also differences during construction. Repairs are much stricter, especially on tread joints.