I’m experimenting on the Gt3 Touring for a wheel setu. once the Speedster arrives, I will swap the Forgeline’s over and complete the modern throwback look. I am still sorting out the rear tires as I did a 21” rear. The standard Michelin in 305 width isn’t a Porsche N Spec, therefore looks too narrow. Porsche N Spec is wider than a standard 305. The 315 tire in 21” is only in MSpec for Mercedes. It looks to be narrower than a 305 based on data published on TireRack