They should run about 80Cish. Mine did that as well, as soon as I replaced the t stat the temps would come up to almost 100C on the highway. As it starts to warm up over the next couple of months I will have to clean out the radiator.

Your radiator is clogged, either internaly or externaly.

__________________
1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200