Tire load rating

[ktm505sx]

Hey, i intalled a 35x12.5-18 pro com xtreme a/t with rim 18x9-12 offsets

Well the thing is i m getting a lot of steering shake at low speed on a rought offroad trail, compared to a extended cab raptor with stocks tires. It doesnt have that problem on same terrain

I guy on the forum told me those tires that i have on my truck are tire E rating, says those are very heavy tire for a raptor. It could be the cause of the roughness of my svt raptor.

So i checked for others tires options
Stock tires 17, tire load rating D 2910@50psi max load

General grabbers 18, tire load rating E
3415 max load

Pro comp tires 18
Tire load rating E 3415 max load

If i install the gt grabbers, it would be the same as the pro comp xtreme a/t

How do i get out of my truck's steering shake and roughness.

Do you think it would be the 18x9 -12 offsets rim?

 

[rubberdust]

you have a couple things at work here, although the fact that you have load range E instead of load range D is most likely not the primary issue.
The difference between load ranges on tires is a result of the tires ability to hold a higher inflation pressure! It's the air pressure that carries the increased load. While it varies by tire brand a bit, the difference in the tires between a load range D & E typically is a stiffer or stronger belt area and/or stronger sidewall cord, varying combinations of these allow the tire to be inflated to a higher psi. Neither of these additional reinforcements are an automaticly going to make for a harsher ride.
The difference in tire sidewall height is another factor. A good rule of thumb all things being equal is for every 1 inch increase in wheel diameter you will decrease tire sidewall height by 1/2 inch this results in about a 10% increase in sidewall stiffness! The good news is better handling on the street, the bad news is a shorter less compliant sidewall to absorb shock.
The negative 12 offset of your wheels is an area that can cause real headaches. By increasing the track width you increase the stresses on everything in the suspension reducing it's ability to deal with any surface irregularities that can lead to a shake.
The last item is the tire & wheel assembly balance. Dynamic wheel balancing addresses both up & down (hop) & side to side (wooble), I still see in too many instances where a static balance is done to avoid placing wheel weights on the face of the wheel, that eliminates the up & down (hop), but does NOTHING to address the side to side (wobble).
It maybe as simple as having a dynamic balance done to your wheels & tires, but I suspect that your wheel offest is going to be the area that may need to be changed.