Mixed Tire Size

So I grew up with awd cars and they always had to be flatbedded or MUST have all tires the same size.

My question for everyone is that if you buy 4 new true 35's or even 37's, why are you still running a stock spare? What happens if you put your stock spare on the rear, with the diff locked or up front and 4wd engaged? Isn't that "BAD" for the truck?

Thanks for allowing the noobness.

Chris

Yes bad. If you have to run a smaller spare run it in front and only in 2 wheel drive.

From what I have seen here is that most change out the spare too when getting something drastically different.

That's what I figured, which is why I would buy 5 new tires, but I've seen some people with different tires on 5/6 vs the rolling 4. Thanks for confirming.

You can get creative with air pressures as well. More pressure in the shorter tire and less in the taller tire. Measure the loaded radius to get them close to equal. One of the 4x4 mags did a writeup about it not too long back.