[1MtnGoat]

For what it's worth!
Factory Tires Goodyear F1 G2 285/35-20 $429 TR 305/35-20 $449 TR
Michelin Pilot Supe r Sport 285/35-20 $358 DT 315/35-20 $452 DT
Michelin Pilot PS2 305/35-20 $483 TR
Nitto Invo 275/40-20 $247 DT 315/35-20 $291 DT
Continental DWS 275/40-20 $269 DT 315/35-20 $255 TR

TR=Tire Rack prices are plus shipping.
DT=Discount Tire prices include shipping.

315/35-20 tires are +0.3" in diameter. My service mgr. tells me 0.3" should not cause a problem. The size can be programmed into the ECU.