Road Force Measurement - Hunter 9700
#1
Road Force Measurement - Hunter 9700
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
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
#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.
#5
TECH Apprentice
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.
#6
Originally Posted by 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.