2008 ram 1500 overheating

[rainman251]

My eingine temeperature starts out normal, then after about 20 minutes of highway driving the needle climbs to the high side. I turn the heater on to control it after that, but it stays running hotter than normal. The radiator fins have been washed free of debris, coolant level is visible in the resevoir, the fan spins and I just changed the thermostat. Used a laser thermometer and only got 205 as the top temp. Any ideas?

[snowman2006]

what about the temp sensor!

[slippyflaw]

and make sure you have no air pockets in the cooling system and make sure the thermostat is good when it runs hot make sure the top and bottom radiator hoses are the same temp and pressure