I have been reading and searching this subject for a couple days now and looking for some more insight.

My problem is that my car vibrates once i reach 70 mph and does so until I reach 80 mph, and then it stops. Its super smooth except when I am going 71-79 mph. The vibration can be felt in the steering wheel and the seats and its very annoying. I have Yoko s-drives that have about 4k on them which are on 20 inch sevas s-7's. They are properly aired up as well.

I thought it was the hub rings, but I just got it back from discount tire and the vibration is still there. I am thinking my next option is to rebalance them.

Its just weird that it only vibrates between 71-79 mph. If you have any advice I would greatly appreciate your input, and Thanks in advance!

 

Not weird at all!
Compare the tire rolling circumference [one bad spot every rotation] with speed and you will see the vibration frequency in HERTZ.
When the tire/wheel vibration matches the chassis stiffness frequency whamo they reinforce each other. Change either and the summation products MOVE [in speed] and or intensity.

25" x pi = ~ 78.5" 71/60= 1.183 x 88= 104 ft/sec or 15.8 Hz

Things they teach in college physics and high school math.

Make sure the as mounted [hub centric ring problems] TIRE radial force stiffness variation is below 5-7 pounds or these things develop.

The frequency is too high for shocks to damp out so the tire pushes the body up ward every time the bad spot is at bottom against road.

 

get it rebalanced.

 

Thanks for the information. Talked to a n infiniti dealership and they quoted me $86 to check them on their machine, but I dont think that includes rebalancing them. I will let yall know how it goes.

 

you can get tires balanced for cheaper than that at local tire shops... it cousted me 50 to mount and balance 4 tires so dont go the dealer and i've many horrible stories on the boards from peopple going to discount tires.

 

A radial force machine test is $25-$50 per tire. A standard balance machine cannot diagnose the radial force caused by bent warped wheels or defective worn tires.

 

I spoke with an infiniti service rep here in dallas, and he said it was going to be $86 on there hunter radial force balancer for all four wheels. So hopefully he didnt miss quote me, but ill know for sure this weekend.

 

is it more of a honning sound like wahwahwhawhwha..wobbling feeling?

could be wheel bearing...
i just had my mech test drive mine..

mine starts at 20+ till all the way, feels like an unbalance tire. but it did the same thing on my 17s n 20s...

hopefully urs is just a balancing problem, let us know what u find out

 

One thing to be aware of as i found out recently, some after market rims comes with shims that fit inside the rim so that it hugs the ring thats around the hub nut. If not put in it will vibrate at certain speeds.

 

I never got any shims from sevas when i got my wheels, so hopefully that isnt the problem.

 

They may be already on. just pull one off and feel inside the hub or see if its attached to the hub ring on the car. on my axis without the those shims it is alot of room in there to do some damage!

 

check your wheels bearings..i just had this problem fixed.

my car would start to shake/vibrate as i got to 20mph and wouldnt stop unless i reached speeds above 75

i went to the dealership and they wouldnt believe that it was the wheel bearing, but replaced it anyways

no noise now =)

 

weird how it happens only at that range.

sorta like how my old delorean would start making sparks around 88mph.

 

I wish that ^ was my problem!

 

I had the same problem. Find a local shop that has a Hunter Road Force Balancer here http://www.gsp9700.com/pub/search/findgsp9700.cfm

I took mine in several times and they kept telling me the tires were balanced. I took it to a shop that had the Hunter and it is now perfect. Road Force balancing is the only way to go.