i have learned that there is the speed limiter on my 92 RS of 108 MPH because my tires are not 'Z' Rated, i have a set of Eagle GA's, they cost me like $150 around there a piece, how do i tell if like after this weekend when i reprogram the chip to bypass that if my tires are gonna blow up when im doing like 125mph?

any ideas or thoughts?

 

Im not sure if this is this is the answer to the right question, but if you want to know if your tires are Z rated, they will say on the side before the first set of numbers.

 

what does it mean to be Z rated?

 

here are all the definitions of the speed ratings

Q-speed rated Capable of speeds up to 100 mph.*


S-speed rated Capable of speeds up to 112 mph.*


T-speed rated Capable of speeds up to 118 mph.*


U-speed rated Capable of speeds up to 124 mph.*


H-speed rated Capable of speeds up to 130 mph.*


V-speed rated Capable of speeds up to 149 mph.*


W-speed rated Capable of speeds up to 168 mph.*


Y-speed rated Capable of speeds up to 186 mph.*


Z-speed rated Capable of speeds above 149 mph.*

 

I want Y rated tires then, right?

 

Z is the best. Note it says "above" instead of "up to".

 

The following statement came right off the Tirerack.com website. I would disagree that Z rated tires are the best!

"When Z-speed rated tires were first introduced, they were thought to reflect the highest speed rating that would ever be required. Since that time the automotive industry has found it necessary to add W- and Y-speed ratings (indicated in the tire’s service description) to identify the tires that meet the needs of new vehicles that have extremely high, top speed capabilities.

Miles/Hour Kilometers/Hour
P225/50ZR16 149+ 240+
P225/50ZR16 91W 168 270
P225/50ZR16 91Y 186 300

While all Z-speed rated tires are capable of speeds of 149 mph and above, prior to the W- and Y-speed ratings were identified in the service, how far above 149 mph was not identified."

Z-rated typically is for 149+ but how long will the tire last at sustained speeds of 149+ was not known. Thus the entrance of the "Y" and "W". They are rated at higher speeds and can sustain long distances up to 186mph (Y) and 169mph (W).


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