switch from 265 to 285 tires

Behold: The NorCal mod for Chevy trucks. Shown is on a GMT900, but works on 800s too.


https://www.duramaxforum.com/forum/nor-cal-truck/69677-2007-5-2014-nbs-hd-large-fender-mod-step-step-pics.htm

The 'Burban runs (and clears) 295/65-18s, which is a 33" tires, with a 1.5" lift in front, and one in back.

The mod took one hour on the first side, and about 15 minutes on the second side.

BTW, talking about a tires width (265 or 285) without knowing its aspect ratio and wheel diameter, or overall diameter, is a waste of time.

Happy cutting and modding to all Chevy owners who check out that link...

:-)

ScottG wrote:

monkey44 wrote:
I put BFG 285 on my 2015 Chevy 2500HD 4x4 DCab- 4:10RE - Stock Rims - NO problems, no rub, rides and look better in my opinion. The install was done at my local Chevy dealer, so he had no issues with the stock rims and 285's...

I took off General 265's - there was some issue with the stock tires, and dealer was changing under warranty. I paid a little extra and had him install the BFG 285's instead. Great fit, no issues highway or back-roads.

Regards the gearing issue -- I do not notice any difference in the power between 265s and 285s, and we haul our camper in the Rockies as well as flatlands ... I also notice MPG similar hauling the camper, but a slight MPG increase when empty on the highway - not enough to matter or even notice, although I have no real world comparison documented.

I would not expect you to notice a gearing difference with just a TC on. The difference shows up when you load it down with a heavy trailer.

Scott - yes I agree with you about TC vs TT ... however, we did notice a difference in the ride with the new tires, significant difference. I've always bought BFG AT tires, years in the building trades and years camping. We always had HD trucks ... only once a 1500, and it would not do either job ... TC only weighs about 3000 lbs, so fairly light compared to some but still needs the 2500HD ...

I do notice quite a difference tho in the 2003 HD - 4 spd w/6.0L at 3:73, versus the 2015 6.0L-6 spd and 4:10, altho some of that is newer engine tech and performance I'm sure.

Every tire has specifications and one of the columns is recommended rim width.

• Narrowest will provide the best 'Ride Quality" and the most sidewall bend back
• Widest will provide the best handling...for that rim width & tire...AKA smallest slip angle, and the lest sidewall bend back

Decide which is more important for youselves. Mine are 10" wide vs the tire recommendation of 8" wide for a LT265/75R16E. Exactly what I want: ride quality is horrible and the slip angle is very smalle

Better to use "Rev's per mile" to review the effect on your engine rev's/speed you wish to be at. Need your ICE's torque/HP curve to do so effectively. Along with all of the gear boxes from the ICE to pavement. Of course need the OEM info as a datum

What hasn't been discussed is the wheel off set. Ditto needing OEM spec in order to figure this out

Then measure both static and dynamic dimensions THROUGHOUT the travel for both sides of steering wheel lock to lock. That will tell if it will rub

Why more and more of the large installer corporations won't mount anything other than OEM for 'that' vehicle. Costco was one of the first to do so. Many independent franchise owners will, but they will have fine print to CYA themselves

This might help, but do so at your own risk (my CYA)...most fender sheetmetal will have a bend back lip on the wheel opening. That is the most likely part to rub, along with the forward and rearward corners. Get a 2" dia water pipe (steel) about 4'-5' long and roll it along that bendback to fold it upwards into the fender...but that will only solve the upper bendback interference

Have always loved over sized tires and have no problems with using a saw-zaw if needed on my trucks. Cars is another topic

monkey44 wrote:
I put BFG 285 on my 2015 Chevy 2500HD 4x4 DCab- 4:10RE - Stock Rims - NO problems, no rub, rides and look better in my opinion. The install was done at my local Chevy dealer, so he had no issues with the stock rims and 285's...

I took off General 265's - there was some issue with the stock tires, and dealer was changing under warranty. I paid a little extra and had him install the BFG 285's instead. Great fit, no issues highway or back-roads.

Regards the gearing issue -- I do not notice any difference in the power between 265s and 285s, and we haul our camper in the Rockies as well as flatlands ... I also notice MPG similar hauling the camper, but a slight MPG increase when empty on the highway - not enough to matter or even notice, although I have no real world comparison documented.

I would not expect you to notice a gearing difference with just a TC on. The difference shows up when you load it down with a heavy trailer.

I put BFG 285 on my 2015 Chevy 2500HD 4x4 DCab- 4:10RE - Stock Rims - NO problems, no rub, rides and look better in my opinion. The install was done at my local Chevy dealer, so he had no issues with the stock rims and 285's...

I took off General 265's - there was some issue with the stock tires, and dealer was changing under warranty. I paid a little extra and had him install the BFG 285's instead. Great fit, no issues highway or back-roads.

Regards the gearing issue -- I do not notice any difference in the power between 265s and 285s, and we haul our camper in the Rockies as well as flatlands ... I also notice MPG similar hauling the camper, but a slight MPG increase when empty on the highway - not enough to matter or even notice, although I have no real world comparison documented.

Thank you all, Gear ratio is something I never thought about. I think I will just stick to the 265's ive used for years. Thanks for all the info.

ScottG wrote:
I made that exact change and it screwed up my gearing bad.

I have done the same thing on my '18 Chevy 3500 SRW. I am pulling the 285's off. Looks cool, great in deep snow, but the mpg penalty is not worth it. I have clearly pulled the L5P out of its optimum ratio.

ScottG wrote:
I made that exact change and it screwed up my gearing bad.

I was thinking about this too! If one has 4.10s, you go from a 245 size as noted to a 265, you've effectively lowered the ratio to a 3.95. A 285 to a 3.73. If starting at a 3.73...> 3.55 @ 3.42 effective ratio. A gear change @ 1500 per pumpkin if an 8 lug gets pretty pricy.
My 88 with a th400 3.73 gears was noticeably worst. My 96 6.5rd with 4.10s and 5 sp manual imho made it a bit better...still noticed some initial loss of power on take off. A bit better rpm on freeway.

Marty

I made that exact change and it screwed up my gearing bad.

I need to point out, which I did not do well earlier. What I mentioned doing, is what I did to my 88 and 96 8 lug GM SW 3500 trucks.
As noted, you will have to try it.out, measure etc.
I do not see anyone discouraging you by any means, just be cautious. An FEA may be needed depending on how tires sit, steering after adding taller and wider tires, longer shocks......

Marty