New Tire Time

[lipets]

I have the org 275/75/16 just nearing 60K, planning a big trip was thinking about upsizing a bit to a 265/75/16

 

I assume the slightly larger tire about an inch will increase MPG by a little bit.

 

Any thoughts or leave it stock.

 

90 % highway, 50 % towing a RV at about 6,000 lbs.

[xwire]

going from a 275/75R16 to a 265/75R16 is DOWN sizing

 

the 275 (or 265) refers to the width of the thread in mm's the 75 it 75% of the width to for sidewall height

[5-0stank]

285s would look good.

[lipets]

Bridgestone says

 

LT265/75R16 dia 31.2 width 8.2

 

LT245/75R16 dia 30.5 width 7.3

 

So in this tire the 265 is about 1" larger

 

Now back to my question will that extra dia increase MPH

[thearborbarber]

No, I tried that on my 2004 2500hd. No change in mileage. It only lowers RPMs by 100-200. The speedo will be off by 2 mph. The little you lower the rpm's is offset by the additional tire weight. Wheels and tires are considered un-sprung weight. Weight that is not supported by the vehicles chassis. Un-sprung weight sucks up power. The old rule of thumb is for every 1 pound of un-sprung weight you lose is like loosing 100 pounds of sprung weight.

 

In your original post you mention going form 275's to 265's. I believe that is where the confusion began.

[xwire]

Bridgestone says

 

LT265/75R16 dia 31.2 width 8.2

 

LT245/75R16 dia 30.5 width 7.3

 

So in this tire the 265 is about 1" larger

 

Now back to my question will that extra dia increase MPH

 

 

now going for 245's make more since... in your first post you posted about going from 275's to 265's

 

and no that is not enough of an aspect ratio change to make a noticeable change in end gearing

[rodram]

To LI Pets .... read your original post, I think you had a little typo in there.... anyway...

 

... to answer your question .... if you want to go from 245s to 265s then at 60 mph ACTUAL speed, your speedometer will read about 58 mph.... or when your speedo reads 60, you will actually be going a little faster than 60.

 

... your actual miles per gallon fuel consumption really won't change, but if you take the odometer reading and the fuel purchase, it will look like a good mpg, but you would have actually driven a little farther than the odometer indicates.

 

... tires are a personal preference... personally I prefer to stick to OE size and grade (ie., 8ply or 10ply), particularly when using the truck to pull a trailer

 

... your slightly larger diameter tires would take away a little bit of torque for trailer pulling.... if you have 3.42 gears this might be really noticeable, if you have 3.73 or 4.10 gears, it may not be an issue...

 

... in my opinion, there are much better tires out there for aftermarket supply that are a far better choice than replacing your original tires with the same brand... check out TOYO or Michelin or BFG or Cooper.

[Kodiak450]

Going from a 245 to a 265 you'll notice better performance when you hit puddles , especially at highway speeds (also depending on tire). Handleing, any 265 will feel better then a 245, you'll notice a slight improvement. I always run BFG AT's thicker ply tire (8-10 ply) and noticed gas mileage is a little worse cause of heavier, bigger tire. But my truck is my company truck and I use it for work, and snow plow with it, so a strong reliable, aggressive tire is what I need. Also even though I've personally seen a 285 on a stock GM rim, it is pushing it with that size. GM recommends (at least they do with my year) not to exceed a 265 tire on stock wheels. You also notice a price increase going from a 245 to a 265. I find running them at 50-55 psi they wear nice, anything higher like 60-65 they will wear fast!

 

If you decide to go with BFG AT's in a 265 and can find them for $180 a tire or less, that would be a great price! Last set I think i paid $200 which I thought was high. I've actually paid $130 in the past before the tire spike increase online.

[davzog]

If you increase the tire size there are a couple of things that happen. You do effectively change your final drive ratio....seems like you would gain mpg. However, with a larger and heavier tire you gain unsprung weight which is the worst kind...hence you have more rolling resistance due to increase in size and weight, so you will drip at least 1 mpg...

 

I went from the original 245x75x16 to 265x70x17...speedo was off about 4 mph at 60 (geometrically gets worse as speed increases), lost almost 2 mpg, and lost a noticeable amount of performance due to the change in final drive ratio. Got a Blackbear performance (87 octane) tune and got back most of the lost performance and about 1 mpg....so it looks cool, but cost mpg and $$$ ha

[Kodiak450]

If you increase the tire size there are a couple of things that happen. You do effectively change your final drive ratio....seems like you would gain mpg. However, with a larger and heavier tire you gain unsprung weight which is the worst kind...hence you have more rolling resistance due to increase in size and weight, so you will drip at least 1 mpg...

 

I went from the original 245x75x16 to 265x70x17...speedo was off about 4 mph at 60 (geometrically gets worse as speed increases), lost almost 2 mpg, and lost a noticeable amount of performance due to the change in final drive ratio. Got a Blackbear performance (87 octane) tune and got back most of the lost performance and about 1 mpg....so it looks cool, but cost mpg and $$$ ha

 

Did you also upgrade the brakes when you put 17's on it? Meaning ..put on bigger rotors? Thats what I would have done if you didn't. I was debating to do that, but the expense would add up quite a bit, and finding 8 lug HD wheels seems to be very difficult for me for some odd reasons. Every place I looked, didn't have them at least not in the style I liked. I wanted to get the creager outlaw 2's last decade for a F250 i had, could not find them in 8 lug anywhere.