tire question, promise its a new question

My xj came with 235/75's on it that im assuming the dealer put on. Stock size in the door jam says 215/75. The spare is 225/75? confussed me, but thats not the question. I was wondering if i could go back to the stock width but on a 16" rim with a 215/85-16. By doing this i would go from the 235 = 29" to the 215 = 30.5" and less roling resistance from a wider tire. Has anyone ran this size or anything like it? Any thoughts or opinions?

FYI - Jeep is stock right now and im not interested in cutting fenders at this point but might get a small lift via bastard pack and V8 ZJ coils this summer

How wide of a rim?

i'd prolly search the junkyards for a 16x6 if possible but i know it can be run on a 16x7 as a girl i work with has that setup on a 4runner

also, i know the stock 15" rim i have is 7" wide and came with a 215 on it so it will work

I'd think that should be fine.

Most "31s" really measure out at a true 30.5", or there about. I think Goodrich makes a 15-31x9.00 or 9.50. (a narrow 31) it would probably be cheaper then the 16" tires. Might want to look into that.

reason for the 215/85 size is that i can later upgrade to 235/85 or 255/85 as i prefer skinny tires. also i think it would be very hard to find 9.50's since the only size that i have seen is a 30x9.50 except for TSL's

One comment on the size of tire, While you are decreasing the width of the tire you are moving the bulk weight of the tire out (With the rim weight being .5" further out from center along with more weight to make up the extra 3 inches of material for the extra circumference) along with the tire tread (bulk of the tire weight).

SO while rolling resistance may be decreased, you will notice better Highway MPG but with the increased amount of TQ needed to start the tires rolling you will see a slight decrease with your city MPG...


At least thats my $0.02

magus, good observations and explantion

i tend to spend most of my time cruising up and down the highway so i think my mpg's would maybe increase a hair as long as im easy on it in town

anyone know about recalibrating the speedo? with the 215/85's i would be around 3" taller then stock tires i believe so i would be off a fair amount at highway speeds