150-70zr17 vs 150-70r17

[icyhandlz]

ok well the heading says it all, whats teh difference between the 150-70zr17 and the 150-70r17 (this one is 6 or 7 bucks more expensive) why the extra charge what is the difference??? thanks, this is on acontinental road attack if it matter

[steves]

Z is the speed rating. V would probably be acceptable.

[icyhandlz]

so is the zr better than the r???

[steves]

The R stands for something different.

A letter (R in this case) that identifies the tire's internal construction follows the two digits used to identify the aspect ratio.

P225/50R16, P225/50ZR16

The R in the P225/50R16 91S size identifies that the tire has a Radial construction in which the tire's body plies "radiate" out from the imaginary center of the wheel. Radial tires are by far the most popular type of tire today representing over 98% of all tires sold.

If the R in the size was replaced with a D (225/50D16), it would identify that the internal tire body plies crisscross on a Diagonal and that the tire has a "bias ply" construction. Tires using this construction are for light truck and spare tire applications.

If the R in the size was replaced with a B (225/50B16), it would identify that the tire body plies not only crisscross the tire on a diagonal as before, but that they are reinforced with belts under the tread area. This type of tire construction is called "Belted." Tires using this construction are practically extinct.

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=46

[nightmare]

I think z is the highest speed rating possible for street tires at 180 MPH (as opposed to full race tires).

- J