Tire temps can tell you more than you want to know.
Use a probe type pyrometer and take 3 readings per tire, inside, middle, outside.
Try and do measurements exacly the same way everytime, LF, RF, RR, LR, or whatever, just do it the same everytime.
The most important part:
Write every temp down. The more you write the easier it will be to find out what is happening tire wise. Ambient temp, overcast, bright sun, etc. If you're running de's for 20 min try and have several hot laps and come in after 18 min with no cool down lap. Take tire temps on the hot grid if possible but take temps in the same location everytime. Tires will cool down very quickly. You want to be able to have a repeatable way of doing everything. It is not helpful to have one set of readings after several hot laps from the hot grid and another reading after a cool down lap and back it the pits.
It will be very difficult to have the same reading accross the tire with DOT R type tires. Best guess is 170-165-160 inside out would be damn good. If you had 170-170-160 let out 3psi. If you had 180-165-150 you would have too much neg camber.
If you can't get temps above 150 you are not driving hard enough (working the tire) or you have too much tire under the car.
You may find that you have one front tire, say RF, that is 10 degrees or more hotter than the LF, as the track you are driving has more left turns than right turns.
You also want to take and write down tire press
AFTER you take tire temps.
Always work with hot pressures. You will find that your tires pressures will rise 6-8# from cold to hot (not warm to hot). You are trying to have the same hot pressures when you come in from hot laps when you start taking tire temps.
All of this is general assumptions to get you pointed in the right direction.
Aren't you glad you asked?