[MV10]

Rears should never wear out before fronts, full stop. Depending on the vehicle the fronts will handle 60% to 80% of the braking at a minimum, because anything less would create a steering-control issue. If your rears wear faster, something is wrong. Badly. And you'd know it because handling gets all kinds of squirrely if your rears are braking harder than the fronts.

The other thing is, rotors don't warp. The amount of heat you'd have to put into a rotor to actually warp it would burn a vehicle to the ground. What usually happens is pad-material deposition (brake pad crap "baking" into the surface of the rotor) or simple wear on the rotor. Some folks around here don't like the "I raced cars" angle but I've used temp-sensitive paints on a race car and my rotors saw temps in excess of 1350 deg F (highest temp the paints indicated, and all bands were roasted), and they never warped... and I stopped. Those were plain old bone-stock rotors made out of exactly the same stuff our trucks run. Nobody here is braking down from 170 MPH in the twins. You aren't warping the rotors. Ever.

 

[MV10]

As of today, 52,000 miles, rears are 4mm and front are 6.5mm. I'm told that rotors need to be replaced in the rear as well which feels dubious to me.

2015 Chevy Colorado V6 4WD Crew Cab Long Box. 90% on-road in dry, rain, snow, and ice.

If the earlier statement that new stock fronts are 11mm and rears are 10mm is accurate, I'd say it's time for rotors. That's much wear is shocking to me, though. My big old heavy Suburban didn't need new rotors over 11 years, 150,000 miles and driving in ways that are entirely inappropriate for a Suburban. Out of the nearly 60 vehicles I've owned, I've only replaced rotors on the Viper due to racing and insanely aggressive PFC pads.

 

[MV10]

I'm bringing mine in next week. Will see how they measure out at 52k miles. I think part of the issue is not getting accurate measurements. Not sure what device they use but can see how they could be off a mm or 2.

Surely they'd use a caliper?

If anyone manages to be off by 2mm with one of those, for our own good, they need to consider flipping burgers or joining the ranks of our glorious Welfare State.