Hey guys, Each time I reach 67mph, the empty passenger seat will shake profusely and I do feel a strong vibration under the car. Once I get above 72mph, the sensation goes away. Anything under 67mph is smooth as well. It doesn't matter if I'm accelerating or coasting, It will occur between these speeds. I assume that I have one or more tires that may not be balanced correctly?
Tyres could be the problem, especially if it doesn't make a difference if you're coasting or accelerating.
2mac, Did you have them 'Road Force Balanced' ? I did that with the tires I got with those FRS wheels,, Mich Primacy HP. I shopped around for a shop that dose this type of balancing. It measures out of roundness buy forcing a cylindrical drum against the tire. I had 3 tires fine with 6 lbs of force. One tire measured 21 lbs. Then they balance the wheels conventionally. They can move the tire around on the rim to see if that makes a difference. I was told to keep that particular tire on the rear and I "might not feel it". These were 10 mile old "Take offs" from a dealer,, 17" wheels, 215/45/17 tires. A tire/wheel can balance fine and look fine but have a 'road force' out of true and you would feel it. I may just have a bum tire and will have to replace it if I feel a problem like yours... I'm waiting to add all my goodies at once to my Prius so I haven't tried them yet. Also Buddy, did you use hub adapter rings with those wheels? A Prius has 54.1mm hub centers. If the wheels you bought have larger centers, only the lug nuts are centering the wheel on the hub,,,,, Not the way to do it. The wheel can be tightened down a little off center without them.
Thanks for the info Bill. My wheels are 17x7.54-100 so can I assume that the .54 means that this number refers to the center? The offset is 42 so that .54 is standing out to me.
To know if you need hub center adapters, next time you have a wheel off see if it can be moved up and down on the hub center ring with the lugs off. If that is a tight fit, you might find a shop that does road force balancing. But first, see if the bad tire/wheel can be spotted by a buddy in a chase car. If it is obvious which wheel is doing a little dance you could have just that wheel tested for road force balancing. Good luck!
Got the tires road force balanced when the shop installed the TRD springs and that solved my issue! I did ask about the hub center adapters and they validated that the right ones were installed. Thanks again for your assistance Bill!
