If everything was fine, you swapped a tire, and now it's not fine, I'd def suspect that tire. It's the only thing that changed. If it was a wheel balance issue you would get the vibration at a certain speed, regardless if you were pressing the brake or not. How old is the front tire you didn't replace??? If it has substantial wear on the inner shoulder of the tire that could cause a shimmy under braking.

 

The front tire I didn't replace is only four months old, they are practically new. The rotors were resurfaced two years ago for the first time by the dealer...

 

Warped rotors?

 

Exactly what I was thinking, and with them being cut once already, It would be a good guess that the rotors are the issue.

I never cut rotors, throw them away, buy new, once you make them thinner by cutting them, they warp that much faster.

Just my .02

 

I don't think the rotors are the issue. Today I drove a little faster on the highway and the steering wheel was shaking even without pressing the brake.

 

Ok, then thats easy, you have a bad tire or a bad balance job.

 

Would warped rotors vibrate at a specific speed or no matter the speed you would feel the shaking?

 

When braking they should vibrate at any speed as long as you are applying the brakes, more so as you are slowing.

 

I also think you have warped brake rotors as well...

 

My brakes don't vibrate all the time, it only happens at a certain speed and now I notice the vibration at higher speeds without stepping on the brakes.

 

This has gone back and fourth a few times here. Bottom line is that if you're not stepping on the brakes and you're getting a vibration at different speeds you have a tire / wheel / balance issue. Take it to a tire place that has a "Road Force Balancer", have them check the new tire first, it will show you if you have an out of round tire and it's one of the best balancers out there.

 

Don't know if you're the DIY -type, but I would swap the wheel that's been worked on for one on the rear (or the spare, if the vehicle is so equiped, Well, unnecessary to say, but if you still have a vibration, you can give the wheel and tyre a lower priority in the culprit stakes.

 

One other thing road force balancing does is tells you the optimal way to mount all 4 tires (match balancing). If you went to a place which doesn't have RF balancing and they simply balanced that single tire separately you may get less than optimal result if the previous tires were match balanced.

 

Who has these Road Force balancers? Does the Lexus dealer have one?

 

if they overtorqued the wheel, ive read that can warp rotors, but honestly, it sounds like bad tire or balance job.
try putting spare tire on and leave new tire off and see what happens.