bigger tires in back?

[bistro]

is it ok to put a set of 265 70r17 on the back wheels and use the standard 255 70r16 tires on the front wheels of the expedition? would that be bad for the transmissision /transfer case? i have a set of the larger tires and was wondering if thats smart or not?

[mechhound]

You definitely don't want to do it beings it's a 4X4. It would be hard on the whole drive train.

[MagicRat]

Originally Posted by mechhound

You definitely don't want to do it beings it's a 4X4. It would be hard on the whole drive train.

I agree. This may not be obvious to the original poster, but the larger rear tires would turn slightly fewer revolutions than the front wheels as you drove.

This is okay, if you are just driving around in 2 wheel drive mode. But as soon as you engaged 4wd and started to drive, the entire driveline would 'wind-up' or bind, placing huge stress on everything. At best, the truck would move slowly and the tires would squeal. At worst, you would break parts.