Rexus300

iTrader: (1)

My car currently has the 245/45/18 tires on the 5 spoke GS430 rims. Road force values are 8 lbs for front left and right wheel/tire, 10 lbs for rear left and 16 lbs for rear right (due to slight bent rim-unnoticeable). I do know Lexus are sensitive to balance and road force numbers. Now, my car is smooth at all speed except around 40-45 mph or so where I feel a small harmonic vibration on road surface that are rough or grooved but no where else. Should the dealership try to get the tires remounted in the front to a lower road force number? I am at lost. Michelins should have lower road force values since they are more rounded and not as out of round as other tire brands tend to have.

mitsuguy

iTrader: (2)

Thats as good as you are going to get...

Anything less than 26 is considered good... if you are getting vibration on those types of roads, its just that tread design on those types of roads - its nothing you are going to solve by remounting tires and such...

Michelin's are not more round than any other type of tire, but they, as well as Bridgestone / Firestone, have a little higher quality control than some other manufacturers, so a higher percentage are better...

Byprodrive

iTrader: (1)

Nothing in this world is perfect and tires are no exception, but yes generally speaking Michelin are "more round" than most other tires.

The vibration is most likely from the bent wheel, tread design does not cause vibration. The ultimate balance comes from balancing tire on the car

mitsuguy

iTrader: (2)

And this comes from what experience??? I have worked with all manufacturers over time and can honestly tell you that there is nothing more round about a Michelin tire than any other good brand name tire... I've seen enough road force numbers to back this up. There are definitely tires out there that are worse, but if you compare a Michelin Pilot Sport to a Bridgestone RE050, you will find zero difference on average... Same goes for the truck tires and such. Some of the BEST road force numbers I've seen are on some of the cheapest generic branded tires.

Tread design can cause vibration on certain roads. Have you ever driven on a type of pavement that causes a shudder in the steering wheel? If not, then you might not know what I'm talking about, but there are sections of road around San Antonio (and Vegas) that cause this weird kind of shudder in the steering wheel and sometimes the seat... I have noticed that this shudder and vibration varies a lot depending on the tire that is on the vehicle. On these roads, a tire with a more solid tread design, more of a rib design will have less noise and vibration issues on these roads.

If you would have read the OP's original post, you would have seen that he is talking about a harmonic type vibration on grooved roads. A bent wheel, although may cause a vibration that is speed specific, will not cause a vibration that is dependent upon the grooves in the road...

Rexus300

iTrader: (1)

Thanks mitsu guy for your expert information. I never knew that cars with low pro tires and different thread designs can amplify road surface feels into the steering wheel like a small shutter but I am used to it since it is only on 2 roads in metro detroit that I get these feels for few miles, but other than that the car is fine and smooth up to 90 mph and more. I learnt that contis and pirellis are softer compounds and you don't notice any feel or changes in it on different road surfaces with the GS especially.