jb442

iTrader: (4)

For those of you who've had your wheels balanced using a Hunter 9700, I'd like to hear the Road Force values for your wheel & tire combination. I've searched around and I can't seem to find any indication as to what an "acceptable" value is, or at what value where you're likely to feel no vibration from the wheels. I just got a new set of 275/40/17 Nitto 555's (which are replacing other "new" tires with high road force numbers) and I think one of new Nittos is causing a vibration at crusing speeds... Which is 75-80mph around here.

I wasn't able to watch them do the balancing this time, but the road force measurements for the new tires was from 5 to 16 lbs. Those seem reasonable since my last set had tires in the 40-50 range and they were definitely causing vibration. I think I'm almost getting hyper-sensitive to the vibrations in the car since I've been diagnosing the problem, but I'm curious as to whether 16 lbs. would be considerd an acceptable value? My suspension is fairly stiff since I have Koni SA's and Hotchkiss springs and the 16 lb. RF value is, apparently, enough to be felt with my setup.

I also did an un-scientific test with the wheels, by rotating all of them to the back of the car, spinning them up to ~15-20 MPH and comparing the visible "hop" or run-out. The one with the most weight on it (almost 6oz, compared to 1-2oz on the other three), had the most "hop". I would suspect that this is the wheel with 16 lbs of road force as well.

I'm going to try and get the shop where I got the tires to replace the one with the greatest road-force value... Hopefully, that'll cure the vibration. If anyone has had a similar experience, please share! Thanks

ybaslo1

iTrader: (10)

I don't know about anyone else, but I use the spec of 12 lbs. of road force or less is acceptable.

SVT WUT 7

For passenger cars anything more than 12lbs is in the red. It gets higher for SUV's and trucks.

jb442

iTrader: (4)

Thanks for the info... Does it actually show 12+ lbs as being out of spec on the display of the 9700? These are brand new tires and I was honestly expecting sub-10 numbers for all of them. I called the dealer today and they're willing to replace the tire that was 16lbs, so we'll see how it goes this Friday when I get it changed out.

GMTECH4

i think 25lbs of road force is the limit for passenger tires. if you have nittos 555r's get used it. mine vibrate also when they get hot they ride better. also anther thing i would look into is, if you do burn-outs hard accel's the tire can spin on the rim and cause a balancing problem (that's why i don't use that slick gel to mount tires). mark the rim and tire with a strieght line and see if at anytime the tire moves on the rim. also you can have a tire that has acceptable road force and still be out of round. i could go on and on about tire vibrations but pm me if u have anymore questions.

jb442

iTrader: (4)

They're just 555's, not the R's. I did get the one tire replaced today, and the road force number was down to 15lbs on this new tire, which is down from 19lbs on the last tire (they told me it was actually 16). So, this is a 4lb improvement and also the wheel only needed 3oz of weight vs. 5.75oz of weight for the previous tire. This tire is going to start out on the back of car, and will eventually be rotated to the front since they're all the same size. Hopefully this cure the vibration. If I could pay more $$$ to get a set of tires that would produce less vibration and better road force numbers, I would, but no one suggested that a more expensive tire than these would produce better numbers. It's getting to be too time consuming to take the tires off and back to the store and have them rebalanced.