how big is 265/70/r17? how would you read this?

[orangeblast22]

so I'm trying to educate myself here

265 is the diameter

and the 70 is???

the R17 is my 17inch rim...right?

I plan on doing the 3" front and 2" rear spacer lift and would like to add some better tires...the stock dunlops are crap eh?

I do not plan to offroad too much but when I do...want my runner to be capable of doing sum stuff...

would appear that people are running 265/70 tires...is this a 31 or 32? and how much of a performance decrease would this be??

just plan to mostly drive onroad rather then off road...but when I go camping would like to have good A/T tires

thanks!!

 

[alpha]

there's plenty of threads about this. a quick search would heed a good amount of information..

but quick answers..

265 is the section width of the tire.
70 is the aspect ratio of the tire, measured in percentage.
R17 is the diameter of the rim it can be installed on.

the stock sizes comes out to about a 31" and the 265/70s come out to about a 32".

i believe this results in a 2mph off reading on the speedo, overread i think. you'll be going 2mph slower than what the speedo reads. and i think it affects the odometer by 2%.

This link should help some.
http://www.miata.net/garage/tirecalc.html

And for more info on tire spec, there's some good basic detailed info on www.tirerack.com .

edit: ha, quick check with the tire size calculator.. looks like i had those values backwards. going 2mph faster than the speedo reads.. hmm.. could've sworn i read in some threads what i posted above.. oh well..

 

[orangeblast22]

so going from my stock dunlops (which are 31s) to the 32 (265/70) there wouldn't be a huge decrease in performance?

going with roughly a 31.6 tire would be pretty good for the occasional off road adventure? nothing heavy of course be good enough to get around?

I was looking at those REVOS...heard nothing but good things about them.

if I went with 265/75/r17..Id have almost a 33...which would then begin to kill my performance I would think...not to mentioin rubbing.


perhaps 265/70/r17 is my best choice? especially given the 3"front and 2"rear cornfed spacer lift yea?

 

[sharp4runr]

And if you search, you'll know that the 265/70/17 will still fit in the spare :

 

[HuntRunner]

so I'm trying to educate myself here

265 is the diameter

and the 70 is???

the R17 is my 17inch rim...right?

I plan on doing the 3" front and 2" rear spacer lift and would like to add some better tires...the stock dunlops are crap eh?

I do not plan to offroad too much but when I do...want my runner to be capable of doing sum stuff...

would appear that people are running 265/70 tires...is this a 31 or 32? and how much of a performance decrease would this be??

just plan to mostly drive onroad rather then off road...but when I go camping would like to have good A/T tires

thanks!!

Here is a formula to calculate the tire diameter in inches from a metric size tire:

TireDiameter = ((2 x SectionWidth x AspectRatio) / 2540) + WheelDiameter.

For a 265/70-17 tire, the equation would look like this:

((2 x 265 x 70) / 2540) + 17 = ~31.6".

Effective axle gearing, and engine rpm, change by the same percent as the change in tire diameter.

Swapping from a ~30.6" tire to a ~31.6" tire is a change of 30.6 / 31.6 = ~0.968. 1 - 0.968 = ~0.032, or ~3.2%.

If your stock gear ratio is 3.73, then 3.73 x 0.968 = ~3.61. Your truck's effective axle ratio after the tire swap would be ~3.61.

 

[OUTRNNR]

Everything you ever wanted to know about Bridgestone Dueler A/T REVO's:

http://www.tirerack.com/tires/Spec.jsp?make=Bridgestone&model=Dueler+A/T+Revo

As far as performance goes, I've heard both ways. Some people say that the car feels more "top heavy" and accelerates slightly slower, and some say no difference at all. There will definitely be some degree of performance degradation due to the higher sidewall ratio and increase in inertial resistance (the willingness of the tire to spin up and spin down).

What I have heard that does seem pretty consistent is people losing 1-2 mpg on average.

Maybe if all you are looking at is a better tire for camping you should consider the 65 series REVO instead of the 70?

 

[Koz]

Also remember each manufacture's tire/size is made to different specs. If you look at the spec. sheet for each tire you will see differences in the overall diameter, overall width, etc. sometimes it might be the difference between rubbing and not rubbing.

Koz

 

[olliebear]

Same as above but this...

265/65/17 is 30.7" diameter. 265/70/17 is 31.7" diameter. Manufactueres differ just a bit so fctor in about 1/4" from "true" diameter. That difference includes tread depth where AT tires have deeper tread depth while HT or all season tires will have shallower tread depth. AT tires like Coopers and BFG will normally use 16-18/32" tred depth while all seasons will use about 13/32" inche tread depth. Rounded treadh shoulders differ from the squared shoulders and squared shoulders tread design may induce some lilght rubbing at full lock as I currently have using BFG A/T KOs.

That extra 1 inch is not really that important in off road use, and I assume that means light off road, fire trials, Class II-III max trials. You get more difference from the tread design--HT/all seasons will not grip slop and slush as well as true A/T designs--and true A/T is not relabled all seasons either. Cooper ST and BFG have large void to lug ratios to grip and handle slop. HT tires like the Dunflops and Bridgetone HT 840 that came on my 4Runner are not slop tires. They can barely grip on snow and rain.

They have thicker belts and more plies under the tread--BFG uses 5 plies on the tread and 3 plies on the sidewall, Bridgestone uses 5 plies on hte tread and 2 plies on the sidewwall, Bridgetone Dueler A/T used on the Hummer 3 uses 7 plies on the tread. The extra tough tread and sidewall protects the tire and allows stiffer plies to roll over rocks nad gravel with less chance of punctures. This is even more so when you up to an "LT" rated tire in C or D load rather than a "P" rated B load tire.

Revos are wonderful tires. Much loved here. I got he BFG A/T KO becasue I had planned for trips where rocky trials and slop is anticipated and I wanted the extra protection that an LT rated C load tire has over the Revo P rated B load tire. BFG is the most tested and proven off light road tire in the business. What it give up to the Revo in wet is made up in greater snow and muck and toughness.

I do suffer a 1- 1 1/2 mpg in penalty--the extra 1", the hearvier LT rated C load, and the At tire design.

 

[Boaz]

your going to loose at least 1.5 up to 3 or 4 mpg upsizing the tires. I paid for it this year on my 2500 mile road trip. I averaged 20mpg this year, and last year I got 22.8 MPG with the stock tires.

On a daily basis, my city MPG suffered a 2 mpg decrease. But I love the ride of the Revos, the look and the better traction in snow, rain and mud.

 

[Bill42]

Since you plan on lifting your vehicle I think the 265/70/17's will fill out the opening better. Getting the P rated instead of LT rated Revos will probably be fine for the type and amount of off-roading you plan to do.

Most here have the P rated. The LT rated are heavier. I have the P rated and did notice a slight change in top heavy (maybe imagined) but now I am used to it.

As for mileage, I have routinely gotten 14.5 mpg. I drive pretty slow and mostly local stop n go traffic. The tire may account for an mpg difference but I can't imagine it is more than 1-2 mpg.

It is outstanding in the rain and fairly quiet. Again maybe I am used to it but I don't notice tire sound at all now.

Your speedo will definitely be off by approx. 2 - 3 mph. Just be aware of it and adjust. No big deal really.

I am very pleased with my Revos.

 

[01thunder]

i want to go from 16 to 17 due to the tundra brake upgrade plus i like the fj cruiser wheels that i bought. i currently have 265/70/16. if i go to 265/70/17, my gas mileage will suffer? i thought that if the tire is bigger it covers more ground at less rpm therefore wasting less gas. am i correct?
and if that is the case, what about just going with the 265/65/17, which is almost the same size as the 16" tire?

 

[ghostridr]

Holy necro thread resurrection batman! :bravo:

Yes, your mpg will go down a tad. More noticeable at city driving than highway.

 

[WXman]

i want to go from 16 to 17 due to the tundra brake upgrade plus i like the fj cruiser wheels that i bought. i currently have 265/70/16. if i go to 265/70/17, my gas mileage will suffer? i thought that if the tire is bigger it covers more ground at less rpm therefore wasting less gas. am i correct?
and if that is the case, what about just going with the 265/65/17, which is almost the same size as the 16" tire?

Adding diameter to the wheel/tire package adds leverage against the drivetrain. It's simple physics. So, there is a fine line. With taller tires you are lowering the RPMs you're turning and saving fuel (on a flat stretch of highway). But at the same time you're fighting the added leverage.

If you just go up one size, and keep your tire weight in check, and don't run a MT tread... then you could gain mileage.

But if you go up multiple sizes and/or use heavy MT tires then you will lose mileage. It's a fine line.

Also.. tire manufacturers always measure from the ground up INCLUDING the bulge of the sidewalls. So the listed diameters of tires will always be larger than what you'll get if you measure the tire from the ground up NOT including the sidewall bulge. Keep that in mind.

 

[01thunder]

Adding diameter to the wheel/tire package adds leverage against the drivetrain. It's simple physics. So, there is a fine line. With taller tires you are lowering the RPMs you're turning and saving fuel (on a flat stretch of highway). But at the same time you're fighting the added leverage.

If you just go up one size, and keep your tire weight in check, and don't run a MT tread... then you could gain mileage.

But if you go up multiple sizes and/or use heavy MT tires then you will lose mileage. It's a fine line.

Also.. tire manufacturers always measure from the ground up INCLUDING the bulge of the sidewalls. So the listed diameters of tires will always be larger than what you'll get if you measure the tire from the ground up NOT including the sidewall bulge. Keep that in mind.

i have a 2wd and don't do any off roading, city and highway driving. plus i live in florida. occasional drive on the beach. so going 1 inch taller will decrease my mileage? if that is the case, i'll just go with the 265/65/17 tire and keep my size.

what are you referring to by gaining mileage?:boxer::barf:

 

[WXman]

i have a 2wd and don't do any off roading, city and highway driving. plus i live in florida. occasional drive on the beach. so going 1 inch taller will decrease my mileage? if that is the case, i'll just go with the 265/65/17 tire and keep my size.

what are you referring to by gaining mileage?:boxer::barf:

I'm saying that if you go from 265/65 to 265/70 and stick with the same style of tire, you could gain a little MPGs (minor gain) from the lower RPMs you'll be turning on the highway.

Once you start adding other variables like going to a MT tread or a heavy tire or whatever... then you start eating up the gains.

 

[01thunder]

I'm saying that if you go from 265/65 to 265/70 and stick with the same style of tire, you could gain a little MPGs (minor gain) from the lower RPMs you'll be turning on the highway.

Once you start adding other variables like going to a MT tread or a heavy tire or whatever... then you start eating up the gains.

right now i have 265/70/16 destinations. i want to go 265/70/17 because i bought a set of FJ wheels that are going on.

if that one inch extra in height is going to make a big difference, even in price, i'll just step it down to 65/17.

 

[wadle5]

Or you could go with pizza cutters and with the narrower tread maybe get a little better mileage. 255/75/17. Will also fit in your spare carrier and will give you a mean looking stance. I almost got those, but was harder to find a shop locally that had that size in my brief window of time.

 

[ebg18t]

Many of us like the pizza cutters. 255-75-17 works excellent.

 

[snivilous]

If you increase in tire size the tire RPM will decrease, but not necessarily your fuel mileage because more torque is needed to turn the same weight tire that's bigger.

I wouldn't put too much thought into mileage change if you aren't changing your tires drastically. If you are saying around the same size and weight then I doubt you would notice a difference because other factors like wind speed and vehicle weight will affect your mileage more.

 

[Sungod]

Holy necro thread resurrection batman! :bravo:

Yes, your mpg will go down a tad. More noticeable at city driving than highway.

I guess you can find things when you search?