I have checked it somewhere, just to make sure I'm right. And I am right, the rims are too wide for such tires. What does it mean? It means that if there is a situation where you will have to make a sharp turn, the load of the vehicle could make your tire go off the rim. The result is that you hear a loud bang as your tire releases all the air, another bang as you destroy your alloy rim when hitting tarmac, and probably another bangs as you slide into something or end up upside down. It doesn't have to happen, but narrow and tall tires make it more probable.
I bought my truck with 245/75/16 tires and:
- the tires are small and the truck looks like crap, or like a skateboard (big chassis, small wheels).
- the tires are small so I run slower than with stock tires at the same RPM
- probably there is an improvement in mileage but with such a big truck, a change in tires doesn't affect it much anyway.
- the tires are crappy on tarmac. There is simply too much load and to little contact surface to stop it and control it.
- on wet roads they are crap, but in fact all tires are crap in wet conditions, these are the laws of physics. When it rains I divide my usual speed by two, to be on the safe side.
- the stock tires for our truck are 275/75/16 so why go smaller than that?
In my opinion the best choice is something like 285/75/16. More tire contact is more control.
Here is a nice calculator to play with:
http://www.miata.net/garage/tirecalc.html