Use this speed calculator to determine your speed with different tires. You must know the rev's/mile of the tire in question.

http://www.cwis.net/~mallie/page12.html

Waylan

 

UHHH-- well, they are and they aren't. They are taller and narrower than 305/70s, but aren't the same height as a 315 tire AT ALL. They are smaller by about the same difference between 285s and 265s. The revs/mile tell the story:

265: 658
285: 636
295: 624
315: 599

Note how the increase from 265 to 285 drops 22rpm. From 295 to 315, you drop 25 rpm, so the difference between a 315 and 295 is actually more than the difference between a 265 and 285.

Now, in terms of PERCENTAGE, things change slightly.

Going from a 265 to a 285 tire is a 3.34% change in revs/mile
Going from a 295 to a 315 tire is a 4.00% change in revs/mile

jlh

 

I'm towing with 285's and 3.55's. Worn the hell out of my rear tires though, I might switch back to the teeny 245's during the summer. They really look stupid. Embarassing. Like seeing your dog with a sweater on or something. But I guess it's for its own good. I may get a set of 305's for deer season though. You never know, those farm lanes can be tricky!

 

Huh, that's not bad. Maybe I should swap in some 4.10s. Where would I be with 4.10s?

 

i have 4.10's and 265's what would be the recomendation for less rpm's on the freeway? i tow quite a bit. but the tach running at 2200 rpm's at 70 can't be good for fuel mileage. what do you guy's think?

 

i don't run any higher than 2000 or so rpm's when running down the interstate because milage drops off, i have a 5 speed manual with 3.54 gears and 285's this puts me at 70 mph at 2000 rpms or so. i would put some bigger tires on.

 

I run about 1800 @ about 75 or 80mph with 315's and 3.55's pretty much just like everyone else states. I don't get the best mileage though, I get between 14 and 15mpg but that is mainly all in town ( got a kinda heavy foot though ) and not much highway driving!!! Without my comp and intake, I got horrible mileage with the bigger tires, it was down around 13 or so...............needless to say I didn't mash the pedal much getting that kind of mileage. Towing with the 315's for me isn't a problem unless I am going somewhat slow and she shifts into OD and then she lugs but with a push of the button and she is good to go!