I recently purchased a 1998 Mercedes-Benz CLK 320 fitted with Roadstone N7000 225/40ZR18 tyres front and back on 18-inch MB sports rims and marked max 50 psi. I don't know what the correct tyre pressures should be for my casual weekend cruising. The tyre importer advised me to run the tyres at five psi under maximum, which seems pretty high to me, and with the same pressures front and rear. What tyre pressures you would suggest?
The tyre importers advice is not correct; 45 psi would be too high, even for high speed touring. Use the factory specs as a guide even though the wheels and tyres are not standard. The specs should be found on a sticker on the inside of the fuel filler cap. If for some reason they’re not there I would suggest you run 32 psi front and back for cruising. You could increase the pressure to 35 psi or so if you were driving at high speed for any length of time.