i have an 07 silverado and I recently upgraded from 17" to 20" wheels with Cooper Zeon LTZ tires. the offset changed by 1mm. The ride is very smooth and quiet but when i apply the brakes around 40mph to it feels like i am running over railroad tracks around the 20mph mark. would the new wheels or tires cause this? they are balanced to a "T". We think it is a brake or rotor problem but i had no issues before the new wheels/tires were installed; the truck ran and braked smoothly. Please give insight to my situation!

 

sounds like warped rotors. Take em off and bring in to NAPA store they can rebalance and smooth them out for cheap, should take care of issue. If not calipers would be next to look at.

 

Since it always happens at around 20MPH perhaps the ABS is kicking in. Could an ABS sensor been damaged while changing the wheels?

If you still have the original wheels try changing back to see if the problem goes away.

 

another thought, the technician may have put the wheels on with an impact gun with no safety stops (ie torq sticks). IF they did this, the torque gun may have warped your rotors. I have seen this numerous times.

I have my reservations about the ABS kicking in, but it couldn't hurt to have them inspected.

I doubt the spacer has anything to do with it unless they are preventing the wheels from being flush with the hubs. Remember, when you are applying the brakes, that causes a shift in the weight balance in your truck. As a result, a greater % of your vehicle's weight will now be on the front axle. So you may not notice a problem with the wheel mounting / spacer system during normal driving. But when you apply the brakes, and more pressure is on the front axle, if there is a problem, this may be when it manifests itself.

But, I would do as SweetEmotion says and take the rotors to a repair facility and have them put them on a lathe. IF they are warped, Trust me on this one, get NEW rotors. Cutting them will only TEMPORARILY fix your problem. Especially on a Silverado.

 

good call on new rotors.

 

Thank you everyone for your input and help. The problem has been solved; the reason for the jerky brakes was the driver's side rear tire. The hull ring was offset hitting the rear brake drum therefore causing a vibration and a hard one at that.

 

wow thats a new one. glad you solved the issue

 

Glad you figured it out. Enjoy the rims!!!