Tire help

[BossChief]

I have a 2011 Nissan Frontier and I need to replace 2 of the tires on it and a friend of mine sold me 2 barely used ones for dirt cheap (100 for the pair) and let me know they aren't exactly the same size.

The stock tires are 265-70-r16

The ones he sold me are 265-75-r16

I brought them to Farm n fleet to have them put on and they called me back saying I really shouldn't put them on my truck because it can screw up my drivetrain being they aren't the same size as the other 2.

I had them hold off on putting them on and figured I'd ask you guys if that's a legit concern (the truck is 4wd).

I guess I've always had matching tires, but the deal was too good to pass on and if I need to, I can resell them.