Ray Magliozzi, syndicated columnist

Dear Car Talk: A friend got new tires for her car but balked at the charge of $70 for tire balancing. How important is it to get new tires balanced? Thanks, I enjoy your column. — Norman

Did you ever stay at one of those roadside Motel 4-and-a-Half places in the old days, Norman? And did you ever put a quarter in the slot next to the bed to make it vibrate? Did you like that? If so, skip the balancing, because that’s how your car will ride with unbalanced tires.

The reason tires need to balanced is because no tire comes off its assembly line absolutely perfect. Good quality tires need less balancing than cheap tires, but they all need some.

The problem is, as the speed of the tire rotation increases, those imperfections in weight distribution get amplified throughout the car. And, even just a tiny bit of extra rubber in one spot will cause a major tooth-clattering vibration by the time you’re going 65 mph.

So, you offset or “balance” those imperfections by putting small weights on the wheel.There are several types of balancers in use these days. There are still some ancient ones, where the wheel is spun very slowly, and a bubble level indicates where the weights should get hammered onto the steel wheel.

The majority of balancers now are high speed, computerized balancers, that spin the wheel very fast and tell the mechanic exactly where and what weight to glue onto the inside of the wheel. And, the best machines are road-force balancers, which simulate the effect of the weight of the car on the wheel and tire. Those also can be useful for diagnosing hard to solve balancing issues.

If your friend’s mechanic had a high-speed or road-force balancing machine, $70 for four wheels is about the right price. The good news is that the machine will still be there when she goes back next week to complain about her ride.

EDITOR’S NOTE: Got a question about cars? Email to Car Talk by visiting the Car Talk website at www.cartalk.com.