Bigger tires on a 2011 Chevy 3500 srw?

SugarHillCTD wrote:
On my 2012 Chevy 2500 I changed from stock to 285/75-17 Dura Grapplers.

Now have 3970# per tire.

My local indy garage (GM guys) cranked the bars up a couple turns and had to zip-tie the rear lower part of the front fender liner back.

Done.

Looks like you found the upper limit by going slightly past it. No adjustments needed with the 70 profile 17" tires.

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/26362225/gotomsg/26863172.cfm#26863172
I have the same tire you're asking about....I have a leveling leaf up front...and just trimmed the corners on the air dam.
Love the tires. Handling and ride are great.
Dave

dave17352 wrote:

Grit dog wrote:

dave17352 wrote:

trail-explorer wrote:
Affecting the final drive ratio would be a big negative for me because I am so used to, and LOVE, the power my truck has now.

As mentioned before, that big of a tire may not fit the front.

Aside from that, and making the Speedo inaccurate, everything else should be fine

That is interesting. So you folks think it would be a big noticeable difference in the power. I am a very conservative driver, seldom do I put my foot down hard. Will it really be that bad?

The difference in power noticed will be negligible on a big diesel. You will drop 1-2 mpg for the heavier bigger dia more aggressive tread compared to a stock street tire.
Personally I wouldn't worry about recalibrating the speedo. Ck with a GPS but you'll only be reading maybe 4 mph slow at freeway speeds.
GMs have tight fender wells. Probably need to level the front end and clip some plastic here and there as mentioned to keep from rubbing at full lock.
The only thing that concerns me is that you think you'll have over 8k on the rear axle. Seems like a lot. More than just a big camper is going to add. A lot of tongue weight on the boat trailer?

My stock tires give 7050 pds rating. My truck camper with 2*30 pound propane full and no water comes in at 6620 on the rear axle. Boat will put me right at my tires limits. Just looking for safety margin. All though I keep it between 55 and 60 when hauling the Truck camper and especially if hauling the boat. Just checking different possibilities. The actual rating of the axle itself is in the 11k range.

So yes, you will be close to 8k on the rears with water and tongue weight. (Glad I've never weighed mine, I might be more apprehensive, hahaha!)
You can get close to 8klbs in srw tire capacity with Toyos, maybe others. My Toyo MT's are rated at 3950#/ea, single wheel, and I had no issues with a long drive up the Alaska highway with a LOADED AF camper and a loaded 16' tandem axle trailer on a 8" hitch extension, but my rear truck tires were more than warm to the touch guessing around 100deg in cool weather.

SugarHillCTD wrote:
On my 2012 Chevy 2500 I changed from stock to 285/75-17 Dura Grapplers.

Now have 3970# per tire.

My local indy garage (GM guys) cranked the bars up a couple turns and had to zip-tie the rear lower part of the front fender liner back.

Done.

I just sent you a pm with a few questions about your tires.

Grit dog wrote:

dave17352 wrote:

trail-explorer wrote:
Affecting the final drive ratio would be a big negative for me because I am so used to, and LOVE, the power my truck has now.

As mentioned before, that big of a tire may not fit the front.

Aside from that, and making the Speedo inaccurate, everything else should be fine

That is interesting. So you folks think it would be a big noticeable difference in the power. I am a very conservative driver, seldom do I put my foot down hard. Will it really be that bad?

The difference in power noticed will be negligible on a big diesel. You will drop 1-2 mpg for the heavier bigger dia more aggressive tread compared to a stock street tire.
Personally I wouldn't worry about recalibrating the speedo. Ck with a GPS but you'll only be reading maybe 4 mph slow at freeway speeds.
GMs have tight fender wells. Probably need to level the front end and clip some plastic here and there as mentioned to keep from rubbing at full lock.
The only thing that concerns me is that you think you'll have over 8k on the rear axle. Seems like a lot. More than just a big camper is going to add. A lot of tongue weight on the boat trailer?

My stock tires give 7050 pds rating. My truck camper with 2*30 pound propane full and no water comes in at 6620 on the rear axle. Boat will put me right at my tires limits. Just looking for safety margin. All though I keep it between 55 and 60 when hauling the Truck camper and especially if hauling the boat. Just checking different possibilities. The actual rating of the axle itself is in the 11k range.

dave17352 wrote:

trail-explorer wrote:
Affecting the final drive ratio would be a big negative for me because I am so used to, and LOVE, the power my truck has now.

As mentioned before, that big of a tire may not fit the front.

Aside from that, and making the Speedo inaccurate, everything else should be fine

That is interesting. So you folks think it would be a big noticeable difference in the power. I am a very conservative driver, seldom do I put my foot down hard. Will it really be that bad?

The difference in power noticed will be negligible on a big diesel. You will drop 1-2 mpg for the heavier bigger dia more aggressive tread compared to a stock street tire.
Personally I wouldn't worry about recalibrating the speedo. Ck with a GPS but you'll only be reading maybe 4 mph slow at freeway speeds.
GMs have tight fender wells. Probably need to level the front end and clip some plastic here and there as mentioned to keep from rubbing at full lock.
The only thing that concerns me is that you think you'll have over 8k on the rear axle. Seems like a lot. More than just a big camper is going to add. A lot of tongue weight on the boat trailer?

On my 2012 Chevy 2500 I changed from stock to 285/75-17 Dura Grapplers.

Now have 3970# per tire.

My local indy garage (GM guys) cranked the bars up a couple turns and had to zip-tie the rear lower part of the front fender liner back.

Done.

wintersun wrote:
Where people have problems is with new rims that are wider and move the load on the spindles further out from the truck resulting in their failing as much from the leveraged loading as from the heavier tires.

Just wanted to add to watch the offset/backspace on any aftermarket wheels. On my 2008, stock wheels had an offset of +28mm (IIRC). A lot of aftermarket wheels have a negative offset which causes the wheel to extend further out. It's a little hard to explain but if you play with the wheel width/offset numbers on the rimsntires calculator you can see the differences.

With my GM 2011 truck I replaced the stock 245/75R17 at 31.5" diameter with 285/70R17 tires that are 32.76" in diameter - only 4% larger tire "height". In reality the new tires provided a more accurate speed and odometer reading with a camper load in the bed than was provided by the stock tires. The larger tires under the camper load have a height comparable to the stock tires with the bed empty. Easy to understand how tire height decreases with increases in load.

A GM with the diesel engine can tow more than 17,000 lbs. so a 4% increase in gearing is hardly going to make a difference with performance. The trucks with the gas engine and the 3.73 gears can still tow 10,000 lbs. (13,000 with 4.10 gears) so a 4,000 lb. camper is a relatively light load as far as the engine and drivetrain are concerned and 4% taller gearing is trivial.

People forget that it is the radius that affects whether a tire will hit anything inside the truck and with a 2" greater diameter the radius is increased by only 1". Same applies to wider tires if they are installed on the factory rims. A 1" wider tire is only going to protrude inside the truck an additional 1/2" and is not going to hit anything. If it did it is simple to adjust the turning stops a small amount.

I saw a gain in stability with the higher load rated Nitto tires (3750 vs. 3195) as there is less sidewall flexing at 80 PSI. I wanted to avoid the expense of new rims and the Nitto's minimum rim width was the same as the factory rims. Where people have problems is with new rims that are wider and move the load on the spindles further out from the truck resulting in their failing as much from the leveraged loading as from the heavier tires.

Forget about having the speedometer adjusted by the dealer. They are forbidden by GM from doing this for any truck. There are aftermarket devices that will enable you to do this. I calculated that with 4% large tires if the speedometer showed I was going 65 MPH my actual speed was 67.6 MPH or not enough to worry about one way or the other. With the camper in the bed at 65 MPH the speedometer shows 65 MPH.

I could not find the factory load rating for the forged aluminum rims but worked backwards from the trucks with these rims. The trucks with these rims have the highest load rating of any of the rims provided by GM. They also make an aluminum rim that is not forged and these have a load rating of less than 2500 lbs. and are not going to be found on any truck with a payload rating provided in the glove box. I found 1-ton trucks with these rims that had a sticker stating that the truck was not to be used with a camper.

DRW is a special case as the tires are not going to be fully inflated and this has an affect on tire height with a camper load. There are likely to be tire width restrictions as well with DRW. In terms of the rims and the tires, with twice as many they can easily handle any camper load. Even at a 2200 lb. load rating the 4 tires would support 8800 lbs., and less the 3200 lb. truck weight, leaves capacity for a 5600 lb. camper load. That is why the manufacturers go to a DRW to increase load capacity for their trucks - it is the easiest and cheapest option available.

dave17352 wrote:

I have the D/A I sure wish someone could find out what the 2011 18 forged aluminum wheels were rated for!

In that case, I doubt you'll notice any loss of power. As to the wheels, don't hold your breath. When I was looking to upgrade I researched the OEM wheels and the most anyone could get out of GM was the wheels are rated comparable to the stock tires. In my case though I wanted to upgrade from the stock 6.5" wide wheels anyway since the minimum recommended width for 265's is 7". I went with 8" wheels rated 3420lbs and my 265 tires are rated 3415.