19.5 wheels and 5th wheels

[sptddog]

I just bought a 2012 GMC 3500 Denali dually yesterday, and it has 19.5 inch commercial tires (I think the wheels are semi wheels, according to the folks on the duramax forums). They believe (the duramax folks) that this will be a big issue towing a keystone fuzion 342 fifth wheel due to the higher bed height. I dread buying wheels and tires after just buying a truck, but will do what I need to do. I don't have the trailer yet, supposed to be picking it up in a week or two (need to get a hitch installed first). I'm hoping the truck isn't lifted (I'm a girl lol, and my husband is not a car/truck guy, so need to get someone to help me out here!)on top of things - doesn't appear to be, but what do I know.

So, thoughts on this? I need to measure the bed more accurately - but my rough estimate was that it was 55-57 inches high, ground to the top of the bed rails. What does a normal 2012 denali with the stock 17 inch tires sit at? I've read that most 5th wheels sit at 58-60 and if that's true, and my measurements are close, I'm not going to have enough clearance to sit level with 6 inches between.

These make the truck look higher in the back, but it really does sit level front to rear - the tonneau cover is deceiving.

Can't seem to get them to load properly from photobucket...

http://s285.photobucket.com/user/sptddog/media/shared__132859820_1.png.html?sort=3&o=0#/user/sptddog/media/shared__132859820_1.png.html?sort=3&o=0&_suid=138866769167805056216630939634

http://s285.photobucket.com/user/sptddog/media/shared__132859820_1.png.html?sort=3&o=0#/user/sptddog/media/shared__132859820_4.png.html?sort=3&o=1&_suid=1388667958154031028198220507674

Also posted on RV Forums....

[ctpd814]

If you get on the tire manufacturers web sight, you can take the tire size and look up the diameter of tires the truck has on it now. You can also do this for the OEM tires. This will tell you if the tires are any taller. By the pictures, the tires look to be a lower profile than stock so they may be the same diameter or at least close. If the tires are close to the same diameter as the OEM tires, you should be fine. Remember the truck will squat a little when the trailer weight is added.

[sptddog]

If you get on the tire manufacturers web sight, you can take the tire size and look up the diameter of tires the truck has on it now. You can also do this for the OEM tires. This will tell you if the tires are any taller. By the pictures, the tires look to be a lower profile than stock so they may be the same diameter or at least close. If the tires are close to the same diameter as the OEM tires, you should be fine. Remember the truck will squat a little when the trailer weight is added.

The manufacturers site says they are 33.2 in diameter...think stock is about 31.8 - so a two inch, or technically 1.4 inch difference. At the end of the day, this shouldn't make much difference should it?

[HDCVO]

Since you have not purchased a hitch yet. I would look at a hitch that has some adjustment in it. I have a B&W that has vertical adjustment to allow for variations in bed height. There are other hitches that do the same. Ken

[sptddog]

B&W companion is my first choice which I think does have adjustments, and I'm told the fuzion hitch has 3 adjustments as well, so praying we can get it to work.

Dealer is asking their service manager for a ground to bed bottom range that will work with the fuzion as well, so hopefully we're in good shape.

[howdy]

I have a 342 and pull it with a 2008 Chevy dually with stock size 16" tires.. I have a Curt hitch that is adjusted all the way up. With the pin box on the trailer in the middle setting I only have 4" of clearance between the bed rails. I lowered the pin box and got my clearance to around 6-6.5". That was a little better, but now my trailer is a little nose high and the rear is a little lower so its not exactly sitting as level as I would like.

I will soon swap out the cheap tires on the trailer on put on some 235/85/16 and that might raise it back up a bit since they are a tad taller than the tires I have on there now. We will see. Having the dealer measure the trailer is nice, but the best way would be to hook up and see how much the truck squats and what the real measurements are.

[sptddog]

Any idea how far your fuzion is from overhang to ground when it's level?

I'm going to cross my fingers that they can get it right, or at least as close to yours and I can put bigger tires on it down the road.

[howdy]

Any idea how far your fuzion is from overhang to ground when it's level?



No. It would not matter on mine, because if the trailer was level I would not have the necessary bed rail clearance. I have to run the trailer a little nose high to get the clearance I need. I also have air bags which I run at 45psi to keep me off the overloads, so that will change things a bit. Best to go down and hook up the the trailer and see how things shake out. Using a different 5th wheel hitch will change things also if it gives you more or less adjustment. I am going to be changing out my pin box here soon for a tri-glide, so it will be interesting to see how that is going to change things.

I can measure the bed rails on my dually as it currently sits with 5psi in the air bags and you can compare it to yours. If yours is higher you could have potential issues. Depends on if they changed the beds between 2008-12.

[sptddog]

That would be awesome if you don't mind doing that! One other measured (can't remmber if it was on this forum or duramax) and was at 55, and one was at 57. I'm right in that vicinity with my half measure I did this morning.

[howdy]

I am at 57.5" I measured from the bed rail to the ground between the rear of the dually fender and the rear bumper. Right by the taillight. That is with my 5th wheel hitch in the bed of the truck. I don't know how much it would go up if any at all when I take it out.

[fsujeeper]

i would rather have 19.5 tires. Those tires should have a higher weight rating than the factory tires. They should also last upwards of 60k miles before being replaced or retread.

[fsujeeper]

Also, after taking a closer look at the pictures the tires look like 22.5 tires/wheels. if that is the case, the smallest diameter 22.5 is around 34.5 inches in diameter.