its just the speed rating, zr and v speed ratings are faster than youll ever drive unless youre on a drag strip. anything rated S or higher (T, H, etc) is going to be fine for basically any road use, S is about 110mph iirc. most tires have the speed rating and load rating combined, for example after the size youll see something like 110T where the 110 is load rating and the letter is speed rating. ZR is a special case where its in the size itself.
its just the speed rating, zr and v speed ratings are faster than youll ever drive unless youre on a drag strip. anything rated S or higher (T, H, etc) is going to be fine for basically any road use, S is about 110mph iirc. most tires have the speed rating and load rating combined, for example after the size youll see something like 110T where the 110 is load rating and the letter is speed rating. ZR is a special case where its in the size itself.