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Old 01-31-2019, 09:23 AM   #1
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Tire size 5er and tow vehicle

I have a 2019 gmc sierra 4wd with 20" tires. Most 5ers it seems have 16" wheels.
Will I have to do anything to the 5er to make it ride level when towing?
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Old 01-31-2019, 09:33 AM   #2
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The height to be concerned about is the truck bed rail height when shopping for a fifth wheel. Ideally, you want a 6" or more clearance to the fifth wheel nose. The hitch and pin box may be adjustable.
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Old 01-31-2019, 09:56 AM   #3
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The two different tire sizes from the 5th wheel at 16" and the truck tires at 20" do not matter.

You may need to adjust the 5th wheel hitch or maybe the pin connection on the 5th wheel to try to level the truck and 5th wheel.

IMHO best to be level or a tiny tiny bit 5th wheel nose high.
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Old 01-31-2019, 09:58 AM   #4
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It depends on the way the 5er is built. Your 20" tires are the same as the 18" tires. 20" tires are lower profile. 18"=32.6, 20"=32.5. 60 series vs 70 series.
Having 16" tires on the 5er will help to make it more level when hitched. Best thing to do is measure your bed height then measure the 5er front overhang height. Figuring that your truck will sag 2" on average you would want a difference between the two of 4" minimum before hitching. You would then set your 5th hitch and pin box so that you're 6" minimum apart. That way when you hitch up and drop 2" everything will be level. Measurements will vary some from mine but thats the process I'd do.
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Old 01-31-2019, 10:13 AM   #5
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Sorry, but if you hitch at 4" between overhang and hitch, when hitched, you'll have 4" of clearance.....Trailer pin box is still bolted to trailer and hitch bolted to truck.....set how it sits when you hook up, then come back on here with answer and then you'll get more ideas on what to do....any sag the truck does being hitched up, the trailer will follow...distance can't grow, unless you high hitched..
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Old 01-31-2019, 10:32 AM   #6
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Bob is assuming there is no air bag on the pin box or fifth hitch.
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Old 01-31-2019, 10:42 AM   #7
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Because of lack of information......
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Old 01-31-2019, 11:03 AM   #8
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thanks for alll the advice. just starting to look for a 5er and wanted some advice about the difference in wheel size. as long as I have 6' from top rail on the truck and bottom of the overhang on the 5er I should be ok. Again thanks to all.
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Old 01-31-2019, 11:03 AM   #9
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that is 6" not 6', dang fingers
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Old 01-31-2019, 12:48 PM   #10
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Quote:
Originally Posted by bob caldwell View Post
Sorry, but if you hitch at 4" between overhang and hitch, when hitched, you'll have 4" of clearance.....Trailer pin box is still bolted to trailer and hitch bolted to truck.....set how it sits when you hook up, then come back on here with answer and then you'll get more ideas on what to do....any sag the truck does being hitched up, the trailer will follow...distance can't grow, unless you high hitched..
I probably wasn't clear in my setup.
If you measure the truck bed at 60" then you need the level 5th wheel front overhang to be at a minimum of 64" unhitched just sitting there. Then you can adjust everything to get 6" bed clearance and have the 5er level when towing.

If the truck bed is 60" and the 5er overhang is 61,62, etc then the 5er will be front high when you get your needed 6" bed clearance.

All is assuming 2" truck sag which seems normal or there abouts.
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Old 02-03-2019, 02:34 PM   #11
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First of all, you have 20" rims. What size are your tires? As others have said tire size does not matter if you can get the 5th wheel clearances on the bed rails.
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Old 02-10-2019, 08:04 PM   #12
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When referring on the bed’s heights isn’t more important to mesure the heights of the hitch because hitch can be at different level but it’s where the king pin will be connected.
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