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Tires bowed in on front 99 gmc sierra

Onyx_gmc1999

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Onyx_gmc1999 Enthusiast

Onyx_gmc1999

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OK so this may be a crazy question. But on my 99 gmc sierra 1500, my tires are bowed at an angle. What could be the main cause for this? Stock Torsion keys are maxed out so I'm hoping buying the rough country keys will help or do I need something els?

arcasey Enthusiast

arcasey

Posted
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Different keys are not really going to solve your problem. Just from the concept of geometry, when you raise/tighten your torsion bars the tires will have what is called positive camber. You should be able to resolve the problem by getting an alignment. If you are going to put new keys on your truck then I would wait until they are installed before doing the alignment.

Onyx_gmc1999 Enthusiast

Onyx_gmc1999

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Truck has 182k miles. So I should get keys then get alignment? It does ride a little rough . but it dont really pull depending on the road

arcasey Enthusiast

arcasey

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Truck has 182k miles. So I should get keys then get alignment? It does ride a little rough . but it dont really pull depending on the road

 

Yes, you should install the NEW keys BEFORE an alignment IF you are going to put new keys on your truck. You probably don't need the new keys if the only reason you were getting them was to try to fix your alignment issue.

 

The reason it rides rough is because raising the front end stiffens the suspension and judging by your picture you probably installed larger all-terrain or mud tires on your truck which are most likely 10-ply tires which have stiffer sidewalls. Those stiffer sidewalls also contribute to your rough ride.

Onyx_gmc1999 Enthusiast

Onyx_gmc1999

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So another words to increase ride quality I should buy bigger keys to keep them turned down get alignment done. I'd like to keep aggressive tires on it just new ones. Any kind of 35's that ride OK ? Or they all like that?

arcasey Enthusiast

arcasey

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Not exactly, your ride quality isn't (theoretically) going get any better than having the suspension in the stock position for which it was tuned by GM. The problem is that even with the larger keys your front suspension geometry is still lifted or altered. The front suspension geometry is what is causing the change in ride quality (minus the effects from the bigger, stiffer tires). I could go into the theory and explanation of why raising the front suspension of a torsion bar suspension will "stiffen" things up but I'd rather just link what others have already done:

 

https://forum.ih8mud.com/threads/how-much-stiffer-will-the-ride-be-after-a-torsion-lift.533484/

 

http://www.gmfullsize.com/tech/torsion401.html

 

Essentially, you are making no changes to the spring force of the torsion bars. No matter their position they are only going to resist the total weight of the truck. They themselves are not getting "stiffer" and then in-turn making your suspension "stiffer".

 

I don't know of any 35" tires that ride any better than any other 35" tire. Again, I think when you get into the all-terrain or mud terrain tires in a 35" tall size, most if not all of those are going to be load range "E" (10-ply) tires and therefore have the stiffer sidewalls.

 

Another determining factor for whether you need keys or not is if you are near the max travel of your stock keys, then aftermarket keys will help give you a little more height. If you are not near the max adjustment then basically aftermarket keys would be a waste of money, IMHO.

Onyx_gmc1999 Enthusiast

Onyx_gmc1999

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So really if I stick with 35's but get all suspension lift and stock keys turned Down it should be a much better ride? ( other than having the 35's ) also do certain shocks make any difference?

arcasey Enthusiast

arcasey

Posted
Posted

So really if I stick with 35's but get all suspension lift and stock keys turned Down it should be a much better ride? ( other than having the 35's ) also do certain shocks make any difference?

 

Yes, a full suspension lift would be better and yes certain shocks can make a difference. Depending on how far you are lifting, (which with your model and the fact that you have 35's I would assume you are pretty close to max on the stock keys) you could probably make your ride a little more bearable by using aftermarket keys and replacing the shocks to something a little longer, or modifying the mounting brackets for the shocks.

Onyx_gmc1999 Enthusiast

Onyx_gmc1999

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That sounds like a plan. I'm probably going to buy aftermarket keys and keep them as low as I can with a 6 inch rough country lift. Along with a 1.5" body lift . better shocks for sure. Just needed to figure out the tire issue so I won't wear new tires uneven

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