________________________________

There are several reasons for larger tires. 
�
One of the primary is that "stock" sized, correctly rated tires for our bricks are getting harder to find, and downright pricey when found. Larger, safely rated tires are much more widely available, with many more choices of use. Primarily off-road, touring, etc.
�
Another is aesthetics. Bricks have big wheel wells, that the stock 14" wheels and tires don't fill very well. They look like toy tires on a toy truck.
�
And another is the improvement in ride and handling quality. I could not believe the difference in my bricks handling, when I went from 185/14 to 235/70R15 on it. It was amazing! moother, quieter, and much more assured. Individual tire choices can differ, so it may not be lots quieter, or lots smoother, but the improvement will be noticable immediately.
�
I put '86 Audi 6-spoke alloys on my '85, and have had 235/75R15 on�the rear, with the latest set of tires in the front being 215/75R15. The 235 profiles were a little too big, and I had clearance issues at turns.
�
There are downsides, also, that need to be watched out for. Increasing tire diameter�lowers your effective torque at the road surface. Since we are SO torque limited to begin with, you may not want to go to the biggest tires you can fit in the wheel wells. There are wheel bearing life issues, not to mention speedometer accuracy problems. 
�
Ask careful questions, decide on your trade-offs, and make your change. Any increase will help. And even if you keep the same effective rolling diameter, but on 15" or even 16" wheels, it will be noticable.
�
Evan Mac Donald