I am running 225/40/18 michelin pilot alpin a4 (non runflat) on the original wheels. They fit fine on both the 7.5j front on 8j rear.
For summer I put on the original tyres on breyton gts-r 18 inch set 7.5j front and 8.5j rear. Again these wheels accept the 225 and 245 rear without any problem.
If you want same winter set only option is the pirelli sottozero runflat. They are the only one making a 245/35/18 winter wheel.