Tires: Tire compatibility, stock tire size, rim sizes

Question
Jack,
I was given a set of almost new tires - P255/70/R16's. The problem is that my 2000 4Runner comes stock with P265/70/R16's.  I'm no cheapscape, but my 4Runner needs new tires and at about $100/per, the set given to me looks pretty good. I think I know that the 265/255 is the width, so I'm thinking the only effect will be a little drop in gas mileage. Do you agree or would you recommend against it?  Thank You, Russ.

Answer
Hello, Russ
There is so little differance you will hardly notice. In fact most tire companys cure these size tires in the same mold, they just change the sidwall markings. They are able to get the extra growth when inflated on the 265 by incresing the belt angles a little during manufactoring. Your speedometer will be about 1.8% faster and the sidewall will drop about .3 inches. What this means is when your speedo says you are moving 60 MPH you are really only going 58.9 MPH. I went from a 235/75R16 to a 255/70r16 on my Chevy truck and had the dealer adj. the computer so the speedometer was right. You may be able to do the same on the 4runner? There is a pretty good tire size calulator at http://www.miata.net/garage/tirecalc.html You can put in your stock tire size and compare it to different tire and rim sizes.

Hope this helps

Jack