Heat Limitations, at what point do you not run, because of heat?

We’ve run them in the Middle East at 132°F and had no issues.

 

I never found any temp too high to motor along in any vehicle.
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DEATH VALLEY, Calif., "average temps, in Summer", around 135, and that was a few Decades back.
People have been and still are living there, so it can't be all that bad.
A "town name" of FURNACE clearly sums it up.

Vehicles operate in all types of Temperature Fluctuations until the Cooling Mechanisms goes offline, just Like HUMANS, except further travel is best on Wheels, but not on Horse drawn Wagons unless Toting a LARGE cache of water.
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Look at deep, hostile and nearly empty Russia lands where it never thaws out.
Mild temps in -40 Degrees F, on a normal day, and at Dark, it drops.
Engines are NOT shut off unless IN A HEATED BUILDING, or run dry of fuel.

 

I slow down a bit on the highway, to take it easy on the tires ……

 

Yeah not how that works. You take someone who's never worked out in the heat before, say a dispatcher and have them tarp a load of lumber on a 100 degree day, I bet they end up in the ER getting fluids. You don't get to just decide heat isn't going to bother you today.

 

Engine and cooling system shouldn't be a big issue with heat. It's your tires and drive axles I would worry about. Id guess most fleet trucks probably don't have axle temp gauges but they will definitely run pretty darn warm on a 100 degree day if you are pushing hard.
Like most everything with heat, slowing down does wonders.