air bag suspension weight increase

[guido04]

My wife and I have a 2015 GMC Sierra 3500 crew cab extended bed diesel with single rear wheel. We had decided on a 5th wheel that was within my tow limits (16900 for 5th wheel), however we are exploring more options by looking at a 5th wheel toy hauler for my motorcycles. Most of the models my wife and I like are not within my tow capacity if I include a 15% buffer. A few people I know recommend adding air bags to my rear suspension, which according to Firestone increase my tow capacity an additional 5000lbs. Coming to the point: Is this actually safe to increase the tow capacity using air bags? If I am correct the only difference between a SRW and DRW is the extra wheel with no change in suspension or frame, therefore airbags should work without adding any additional stress to the vehicle itself. Has anyone used air bags to increase their capacity and have you had any issues? Recommendations?

[WeBeFulltimers]

guido04 wrote:
A few people I know recommend adding air bags to my rear suspension, which according to Firestone increase my tow capacity an additional 5000lbs.

I'll bet my last dollar that no one from Firestone said that their air bags will increase your towing capacity! Actually Firestone and other air bag manufacturers will tell you that their air bags DO NOT INCREASE TOWING CAPACITY that they will level your rig and improve the ride.

Having said that, I installed Air Lift bags with on-board air on my 2012 F-350 SRW and love them for the better ride. My truck did not need leveling as my pin weight is only 2500 lbs.

[tvman44]

Air bags will raise your rear end, but the axles, tires, springs will not increase in their capacity.

[Bedlam]

Paul Clancy wrote:
On the Gm the dually also has larger rear brakes.

Correct. The hubs of a SRW can be removed off the 11.5" AAM and converted to DRW using the other hubs. This axle is very stout and has more capacity than the GM or Ram SRW ratings. This why I pointed out there is a performance measurement of how quickly you can stop under load - It does not specify which components must be used to accomplish this metric.

[guido04]

Thanks for the responses. Not worried about criticism, that's why I would rather ask the question than do something stupid to my vehicle

[JIMNLIN]

op wrote:
A few people I know recommend adding air bags to my rear suspension, which according to Firestone increase my tow capacity an additional 5000lbs. Coming to the point: Is this actually safe to increase the tow capacity using air bags? If I am correct the only difference between a SRW and DRW is the extra wheel with no change in suspension or frame, therefore airbags should work without adding any additional stress to the vehicle itself. Has anyone used air bags to increase their capacity and have you had any issues? Recommendations?

Tow capacity ?? IMO you mean load carrying capacity which air bags helps the trucks rear spring package carry more weight.
However with out increasing wheel and tire capacities you gain nothing. Never overload a wheel or tire.

Your 3500 SRW GM has a 7050 RAWR. These trucks rear axle can weigh in the 3000-3200 lb range which leaves approx 3850-4000 lbs for a payload.
Check out online weights calculator which figures base truck weighs and all added options. Just follow choices given to the weights calculator which gives a GVWR and FAWR and RAWR payloads.

Probably millions of trucks of all sizes on the road using air bag technology to carry the load.

Check out our truck camper forum for modding a trucks rear suspension to carry more weight safely.

[1jeep]

Hmm...maybe this is correct for GM, but Ford uses a different rear axle, brakes and springs on their DRW.

To the op, I can you as I was in your situation last year. Had a srw crew cab long bed diesel, bought a trailer that was at its limits. I recently upgrade to a DRW and all I can say is I will never go back, it really is that much better towing.

[Paul_Clancy]

On the Gm the dually also has larger rear brakes.

[Bedlam]

Frame and 11k lb axle are the same on the DRW and SRW. The difference is the tire, rim and suspension ratings. The weakest component in the system gives you the OEM rating.

I suggest getting an actual rear axle weight of your truck and subtract your tire ratings to get available pin weight capacity. Figure 20% of the FW's GVWR will be the realistic pin weight. If you are considering a toy hauler, the pin weight will be closer to 25% of GVWR.

If these figures don't give the numbers you need for the FW's you like, you need a bigger truck or need to upgrade components of your current truck. WA only cares that you register sufficient GVWR for your truck to compensate for road wear, each axle is under 20k lbs and you can stop in set distance with your current load. The rest of the ratings on the truck are enforced only for warranty. We can discuss what components to upgrade later based on your findings and how you will proceed.

[IDoMyOwnStunts]

You have some misconceptions about DRW vs SRW. While the vast majority of the components are the same, the one thing that isn't is the tires. Each tire can only support so much weight. Your OEM tires on your SRW can probably support 3525 lbs for a total of 7050 lbs (which happens to be exactly what GM rates your rear axle at). If your truck were a DRW, your OEM tires would only be rated for 3085 lbs at 80 psi, but you have 4 of them for a total of 12340 lbs. GM rates a DRW axle for 9375 lbs, so at that point the tires aren't the limiting factor (plus DRW tires are usually inflated to less than their SRW counterparts).

So, the point is that the max you can put on your SRW truck's rear axle is 7050 lbs or you will overload your tires, even inflated to 80 psi cold. Airbags will not increase your tire load carrying capacity. So while your axles, brakes, etc might be able to handle the extra load, your SRW tires are your weakest component. I would highly recommend that you do not overload them.

[Hunterred]

Airbags won't increase your rated capacity. What they do is increase your suspensions ability to handle it's rated capacity a little better. They advertise being able to lift/support 5000 lbs but the fine print on them states to never exceed a vehicles rating. You are stuck with working within your ratings, buying a heavier more capable truck, or deciding to exceed GMs specifications and tow overweight.
You will likely receive a great deal of criticism on this forum, don't take any of it as more than someone else's opinion (mine included). I commend you for asking the question and please ask more if you have. you are exposed to a great deal of knowledge in this place, you just have to wade through the malarkey to find it sometimes.
Welcome to the forum

[jmtandem]

Airbags do not increase your tow capacity 5000 pounds. They increase your tow capacity zero pounds.

[2oldman]

It's been said you cannot increase your GVWR (and other numbers) simply by adding stuff. Others more knowledgable than I will chime in, but no, I don't think simply adding airbags is going to be much help.

Air bags help keep the rear end up, but afaik that's about it.