Has anyone upsized their tires on a newer model dually? If so, what size did you go with and did you use the stock rims. I read somewhere about the widest width allowable with the stock rims, but don't remember where I saw it. Any help would be appreciated.
Unless GM has changed offset on the new duallies, you can run 235 -85 R16 without problem. That's what I had on my last one. They look quite a bit bigger than the 215s. You may be able to go bigger even but I haven't tried it. Of course with custom spacers between the rears, the sky is the limit.
Gm has changed the offset, as a matter of fact, they have specifically designed the wheel to run only the 215/85/16. Does this mean you can't mount a 235/85? No, you can mount it but under load the dual tires will rub each other causing additional heat and possible failure.
Some info from one wheel manufacturer in regards to wheel size and spacers for 3500 trucks(DRW):
This is a common question and the answer is one that most do not want to hear. When Chevrolet redesigned the new 16"x6.5" dual wheel for 2001-current trucks, I had the privilege of working with a GM engineer and Alcoa. I was told they designed the wheel to run no tire larger than an LT215. Their goal was to create less bulge on the tire. They did this by designing a 16"x6.5" rim width, basically .5" wider than a traditional dual wheel. Most would think you could run a wider tire, but they then pushed in the offset and changed the curvature of the wheel. Now to answer your question on the spacer, this is a bad idea. The modern dual wheel is a hub piloted system, meaning the entire weight of the vehicle rest on the center bore. The purpose of the swiveling flange nut is to create a large amount of pressure on the two flat faced wheels against the hub. This allows all the pressure of the wheel to return to the center bore. If you allow an object between the dual wheels you increase the chance dramatically of vibration or stud breakage and you will automatically void your warranty. If you run the larger tire without the use of a spacer, the tires will rub together creating heat and increase the chance of "blow outs". So for the purpose of this discussion by increasing the size of tire you reduce the overall performance and weight carrying capacity of the truck using a 16" wheel.
Modern steel wheel manufacturers can not justify a cost to produce a wheel with a different offset. One reason is the ability to produce enough volume for the tooling and the second is the liability of re-engineering the wheel. Your alternative is to move away from the 16" wheel, but finding a wheel with the correct center bore and offsets will be hard to do. Alcoa Wheels will be producing a 19.5" version wheel that will directly fit on the new Chevy/GM trucks in the coming year. Southwest Wheel
If a 235 bulges that much you might outta ck the wieght of your load, no? our bursh truck is on 235's and they barly show a load with 500 gallons of water and all the equipment we use to fight brush fires. I personally dont have the 235 on yet, maybe someone with them on will take photo's and post 'em. Also my local tire guy said they should not rub, and the 235's are cheaper than the 215's. just my HO.
It's not that the truck is overloaded, it's that the tires are too close together when running the 235s. GM designed the wheel with a different offset starting in 2001. I wish I could run the the 235s also, but I ain't gonna take a chance with my 5er not to mention no warranty work with the wrong size tires on.
I run a 5500 lb camper with stock 215/85 General tires on Alcoa Hotshot wheels made specifically for 2001 and up trucks (supposedly exact width and offset of stock steel wheels). With the camper on and tires pumped to 75 psi, the duals are very close to touching. No way 235's would fit without rubbing.
I'd love to have the 19.5 wheels & tires! I have seen several trucks with this configuration and they looked really excellent, not to mention the tires last like 200K miles, but I can't convince certain folks that $5000 + is a good investment...
My truck unloaded with 80psi there is LESS than 1/4" of space between them at the bulge on the bottom of the tires.
BFG 235-85-16 10 ply
I had a friend put these tires on an older dually with no problems. They looked nice sooooo I went for the switch. I never thought GM would change the spacing on the wheels and leave us with LESS room. Go figure.
Guess I'll save for the "big wheels" and sell mine with the simulaters and all.
looking for the cheapest way to get the big wheel setup.
I tow a 9,000 lb (when loaded) toyhauler bumper pull right now. Looking to get a 33-36 ft 5th wheel by next year. I will have some side pic's by tomorrow...
I do have aftermarket wheels that have a bigger bore. The inner one is the factory steel. The outter has a bigger bore (something like 3/16 or 1/4" bigger) So I had the spacer built with a "lip" to center everything back to the hub. I Also don't see why the factory ones can't be spaced 2" and still ride on the hub. The spacer itself bolts onto the studs using acorn style nuts and not the factory lug nuts. Still the wheel is centered on the hub and then tightened down. The hub seems long enough to center the outter wheel after the 2" spacer is in there also. I'm pretty sure on this, but don't want to mislead anyone. I i'm incorrect, somebody step in from here............
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