Using a infrared thermometer gun

Check them all. If they are all about the same temp, you are good. If one is appreciably hotter than the others, you have a problem.

If you cannot smell them, they are good to go...

Like it was said by another, the thing to watch for s the odd one.

I have seen as high as 130 in the dessert.
I saw 160 once when there was grease on the brakes.

Temps will vary a LOT depending on speed and ambient temps. I've seen 150+ but 120ish is typical. What you are looking for with temps is the outlier. One tire much hotter than the rest. Ten degrees variation is common. Inside duals run a bit warmer than outside. Sunny side runs warmer than shaded side. On a crowned road the right side will run a bit warmer too.

On an Arizona 4th of July I guarantee the reading will lighten your foot. Yet tires endure 160F pavement. Be aware of inequality especially with inner tires. Shoot the bearing caps on the front if you can see them.

My tires have usually run at around 110/120. 275/65 R15 LR-D