Steering wheels shake mainly because the car needs a front end alignment or the tires need to be balanced. It could be more serious though. Underinflated tires could have masked the problem. It could need a part somewhere in the steering.
Make sure yet rotated & balanced the tired well. Most times they do a shitty job of that. I had a car that did that every time I got the tires changed and make sure none of the bout axles are broken because that can cause shaking as well. For now go slower on the interstates. :)
you go by what,s on the door ! if it says 32 pounds cold then that,s what you put in it ! other things also can make it shake, like a belt busted in a tire or a tire out of balance ! it even could be a bad tie rod or ball joint so have the front end checked out to make sure the front end is tight !
run what the tires say. the car doesn't know what tires you have on there. the tire knows what it needs to last
I drove my car home (all interstate) a few hours on super low tires when I bought it, no shaking. It was like 20 psi. The door says 32 and the tires say 44. My dad said split it and I put air in until they were all 41. I drove on the interstate (73ish) on the way to work and about 5-10 miles of 73ish my car started shaking, mainly the steering wheel. It's scary shaking. The guy I bought it from said his mechanic said one of the rear struts needed replaced, but I think it's the air pressure. Nothing else on the car needed done and it's got pretty new tires. Please help, I know nothing about cars.
It's a Toyota Solara SLE Convertible if that helps.