285 tires vs. 265 tires

[Jochen Woern]

The 96 Suburban came originally equipped with 245 tires.

I am currently running 265/75 R 16 BF Goodrich All-Terrain T/A's on my Burb. The tires are starting to get to the point where they should be replaced and I am thinking of going one size bigger, installing 285/75 R16's.

I am however somewhat concerned about the following:

- Will I loose some NOTICEABLE power when installing bigger tires?
- Will I notice a dramatic loss of power while pulling/towing with a bigger set of tires?

I am certainly aware that I will loose some miles per gallon with the bigger rubber, but I do not want to loose some valuable as well as precious towing power. Bigger tires on the Burb look good and I would like to install them, but not if I will loose some important towing power.

Anyone out there running 285's and can provide some input?

Many thanks in advance.

[93GMCSierra]

I could be wrong but increasing the diameter of the tire should make, to a point any way, slower rotation of the drive train with the same actual speed, thus the engine should have a slightly slower RPM, increasing fuel economy.
It would also rob a slight amount of power, kind of like changing the rear gear ratio.
The amount is fairly insignificant at the tire size differences your suggesting though. This is my opinion it could be wrong.

[More Power]

The 285x75R16 tires are 4.4% larger in diameter than the 265's (31.65" vs 32.83"). So, just by the math, you'll lose 4.4% of the rear wheel hp/tq. Larger tires will produce a little less towing power.

And, larger tires produce a little more rolling resistance, so like you guessed, you'll lose some amount in fuel economy due to the increased rolling resistance. Run em hard, and the fuel economy difference will be slight.

Jim

[Jochen Woern]

So, .................. would your recommendation be to stay with 265's?

I mean, I will use every bit of towing power and do not want to loose any, but then I wonder if 4.4% are even noticeable?

Thanks

[joed]

On my 98 3/4 ton 5-spd I had, I towed with both the stock 245s and 265s. The difference was minimal, however it was apparent - the truck seemed to require more pedal/effort to accelerate and go at the same speed.

Fuel economy was also a little lower with the 265s, both in towing and running empty.

Based on my experience, I would recommend staying with the 265s - that seems like a good upper size limit on the GMT-400 trucks.

Joe.

[hogbody]

Unless you have a low axle ratio I would not go up in size any further. I had a 85 Sub. with 245's and I think a 3.21 axle ratio. It has a 5.7 gas. I put on 31x 10's at the time. They were fine when empty but when towing my 8,000 lb. trailer I got terrible fuel economy and pulled lousy. I went back to the small tires and was much happier. The rig looked like crap though.

[TAG]

Sig truck came with 245s, i put on 285 bfg ats a few years ago. Mine has 3.73 gear. Towing power loss was mainly noticeable at takeoff towing 8500 lbs. On road was not noticeable. My mileage did not seem to change, maybe got a little better, but i have done extensive mods on truck since then. Averaging very close to 20mpg during summer months with setup in signature, but with an hp4 program. I got used to the tire size change during the first tow & have not thought about it since. Hope this helps.

[More Power]

So, .................. would your recommendation be to stay with 265's?

I mean, I will use every bit of towing power and do not want to loose any, but then I wonder if 4.4% are even noticeable?

Thanks

245's would likely help your truck to produce the best fuel economy, towing performance, handling and braking performance. Plus, your speedometer will be more accurate. However, I know some upsize their tires more for the look.... which is important too...

Jim

[Jochen Woern]

Thanks very much everyone.

[a5150nut]

JW,

I'm runing 285s with 4:10 gears. It gives me a 3:73 ratio over all. How I know, I have a tweeked VSB re calibrated to 3:73 and speedo is dead on in a mile check. It does decreas towing power.

[CareyWeber]

I'd bet you'll have rubbing issues with 285s. I have 265s and they will rub a certain times. You tow so that will most likely increase the rubbing chances.

Carey

[arveetek]

I'd bet you'll have rubbing issues with 285s. I have 265s and they will rub a certain times. You tow so that will most likely increase the rubbing chances.

Carey

Every truck must be a little different. I have 265's on my K1500, and I've never rubbed at all. I'm considering going to 285's as well, mostly for looks!

Casey

[a5150nut]

To run 285s I had to trim the lower, rear eadge of the front bumper. Not much, but I didn't want to risk cutting a tire.

[KEDDANO]

I'm running 285 Yocahama with 4:10's on my "96 K2500 with no rubbing issue. I pull 10,000# at times and really never noticed much diff,but that could be because that type of weight is always slow on take-off.Mileage did go up some empty. Never checked it hauling the Pulling Tractor(trailer and tractor=10,000+),because most trips are under 60 miles each way....and it would kill me to really know.

[jasondmann]

My truck came with 285's when I bought it from the previous owner. I wanted to keep the look of the larger tire but wanted a little more economy and towing power so I went with 235/85R16. This is a tall skinny tire that is in between the 265 and 285, I got it in the 10 ply and do not have any trouble with it when towing at all. Definitely a big difference in economy I get about 100km more per tank with the skinnier tire.