Kitc2246

Been running Hankook RS4s 245 and 275/40r18 on 8.5 and 10 inch Flow One wheels for two years on a Boxster S. Very happy with the performance and especially the wear. Tire Rack indicated it will be April before RS4s are available this year. Looking for alternative tires and discovering than many optional 200TW tires don't come in 275/40r18. Nitto N01s are an option, but 100TW.

Will a 255/40r18 fit the front and 295/40r18 fit the rear of a 981? How far off the front/rear diameter ratio from OEM can I get without PSM issues?