Sumitomo High Performance HTR Z II Tire (245/45-17). Does anyone know what the speed rating for these tires are? And what would the speed ratings be for tires? eg: zr, y etc. Any help on this would be appreciated. Thanks!

 

The HTR Z II's have a W (168mph) rating.

 

Any z rated tire is rated for 149+, beyond that the V W and Y ratings have specific limits. The letter code will tell you all you need to know, so will any number of reference sites or google. Did you consider wikipedia? http://en.wikipedia.org/wiki/Tire_speed_ratings

I'm not harping on you but seriously... you're going to want to do some research on your own. Never count on what people on boards tell you, even guys like rkaz who are actually right. You can't always tell who's right and who's wrong.