[Mike C]

I have a beater 71 GMC i picked up earlier this year. And I put 255 70 15 on the rear and 225 70 15 on the front. I think the 275 are too big for the front and that the taller tire fills up the rear wheel well better.

Coincidentally, they are the same height as the 235 55 17 and 275 55 17 on my short step which I think is perfect.

Offroad and at the dragstrip, at least aired down at both locales, you get more rubber on the road with the length of the contact patch rather than the width.