Unfortunately they dont do 255 35 R20's.
Ah I never knew that to be honest, learnt something knew there cheers for the info! :-)
Y refers to the speed rating (180mph something). You shouldn't fit a lower speed rating than the vehicle is capable - insurance is one reason, the other is the tyre can break up at higher speeds. Equally your fuel economy usually drops as higher speed rated tyres usually have a greater rolling resistance (extra plys, layers etc in the tread/sidewall over their lower speed equiv)
Excellent price and tyre, thanks OP. For those arguing - really not necessary. I can tell the difference between my tyres, especially when the weather changes. I run 2 sets of 18s for mainly summer and track use and 1 set of 17s for winter. All have different noise, efficiency, and grip profiles (especially in the wet). You don't have to drive like an idiot to notice it either, nor its affect on traction. Judge the reviews and buy for yourself. These are great tyres, not the best race tyres but excellent performance road tyres.
You misunderstood what I said and I'm 12 yo? Ok (lol)