Mike-

That switch definitely made a difference. Those steelies were seriously heavy. But, that did not occur at the same time. I really think my next set of tires is going to be BFG KO's in the 70 series size.

Steel wheels alone lost me about 10 miles per tank. Its nice to have that back.

 

Thanks. I have BFG KO's on my Syncro Vanagon and they are nice. I have read so much good press here about the REVO's that I wanted to try those. I guess I could stick with the KO's. I never had any problems with them on the Synco but then again, it's AWD. Hmmmmmmmm.
Mike

 

I put my KO's through hell and back on my locked 98 Taco and never had a problem. I ran over cacti, rocks, and miscellaneous vegetation. The desert is harsh, and they passed the test.

Cool! A VW with KO's?

 

now you are making my brain hurt. I can't remember it off the top of my head, I will have to consult the BFG fitment guide when I get home.

 

You will never notice a 1/2 inch difference in radius unless you have an engine that has about 6hp. Even then it would be so slight.

The tire is 1 inch larger in diameter. The contact patch is the same since they are both 265s. If anything, at highway speeds you would probably see better mileage since your larger tires are going to take you farther in one revolution than the smaller tires did at the same RPM.

In any case, a 5% change in aspect ratio at a section width of 265mm is small, very small. You will see that much of a difference from different tires of the same size.

 

thanks pistonslap!

 

Well data is data. And I have provided it (corrected). I still disagree with you. Maybe we can agree that we can disagree? I noticed a power loss, not huge, but I could tell and the MPG calculations prove it. Why drag this out?

 

ditto to what christian said. calculations and formulas are one thing, rear world data is another and like christian, i experienced a little power loss and mpg.

bob

 

I took off my 75 muds and put on stock 70s and noticed a little increase in power. More so, I noticed the stopping distance has decreased.

 

Just curious, but do you notice a change in mileage and power when you replace tires of the same size? We are talking about a difference of size that is about equal to that of the difference between a 70/75 aspect ratio with a 265mm section width and a new tire vs. old.

Realistically true gas mileage is almost impossible to calculate. There are so many variables that it would be impossible to accurately detect a .5-1 mpg difference and determine that a 1/2 inch increase in tire radius would change your mpg either way.

 

Piston,

Actually yes. I purchased my current 98 used from a guy in LA. There was about a 3 week lag time before I gave my 99 to my brother.

I drove the new 98 w/ the tires that it came with for almost 2 weeks before I changed out the rims/tires from my 99 (i liked the 5 spoke rims). Both had nearly the same mileage.

Given that its only two tires within a few weeks time, i'd hardly say its statistically significant. However, when I purchased the 32s, there was a difference I felt in the 4runner's ability to accelerate and the gas mileage.

Anyways, I hear where you're coming and I did look at other reasons why my mileage was lower, but from my experience, the tires seem to be the main culprit.

Bob

 

As others have said, I notice with 265/75's my truck is slower and gets worse mileage than with the 265/70's. I don't see the small additional height gained by running a 75 series tire to be worth it...

 

Did you switch to those black steelies at the same time?

On a side note, do you still race? I ran a GT4 Bug in the PA Hillclimb series for years. I also ran it at Pocono (all three infield courses), Summit (Jefferson track) & New Hampshire's road course.

Mike

 

I noticed a slight drop in mileage too BUT doing the math off the tire calculator I am supposed to be gaining some miles.

 

i'm on 265/70 16's BFG AT k/o's. just put on my second set of these tires, no complaints really, until i found them hard to balance as the tread wore down over the years.
i chose the 70's because i drive alot of highway up to the mountains, so alot of high speed stuff and cornering on the way to the ski base. i feared 75's would wear on corners more because of tire roll, and more rotational mass affects braking too.
my .02

 

Just a quick 2 cents - couldn't the main factor for a possible speed/gas loss be the weight? I know that when my friend put Revos one size up (1inch) on his 04, that tire was VASTLY heavier than my stock tire (michelin). When we were putting them all back on , and then putting on mine, you could REALLY tell the difference. Usually when you go to a larger size tire you tend (or maybe just me?) to go from either stock or to something more agressive (more tread etc) Just something to think about.

 

You are correct, its called the "moment of interia" in physics.

Additional rotational mass will take away from acceleration. That is what I was trying to say all along.

 

Yep, I run the black steelies in the winter and off road with a more aggresive tire, and Revos on the stock rims in the summer. I'm sure the extra weight of the black wheels doesn't help.

I've been helping some friends with their road racing cars but I've nothing but an old and basicly stock Mustang to autocross right now. Once I get my kid through school I'll look for something to run. It'll either be a newer Mustang or Corvette to autocross, or an A/Sedan Mustang. Love those American V8's even though a lot of the small cars are faster and cheaper...

 

Your Revo's are 70's on the stock rims? Any pics?

I autocrossed for many moons. Also in a bug. I ran D/SP before building my GT4 car which I ran in E/P. One of my teammates (in Iraq right now ) ran mustangs for a long time in SOLO II. V8's in auto-x are always fun to watch.

Thanks,
Mike

 

My Revos are 70's but I've yet to get any pics up of them. I just got them this spring and couldn't be happier with them. Nice tire, I don't know why for all around use anyone would get anything else. I tried the Dunlop RVXT's before the Revos and never could get them balanced. Sent them back to Tirerack and got the Revos.

You've done a lot more than I have. I've always had wives and kids to cut into my racing budget. The V8 cars are tons of fun to drive. They feel and sound like they're going fast anyway...