Hunter 9700S Print oUt's

[rover3l]

I don't really understand the print out I got from the Hunter machine associated with fitting my new Michelins. It shows a diagram over the 4 tires with a number in lbs associated with it and then there is a separate table with much lower numbers like +1 etc.

It also showed two layouts with the tires in positions for lowest vibration and lowest pull
Modified by rover3l at 12:55 PM 10/23/2004

[Q45tech]

With Michelins the pounds should all be under 5 pounds, unless the wheels are out of spec [very common] when the have more than 60K especially the 2 passengerside wheels which get all the abuse.

Scan and display and we'll go thru it.

At 70 mph 30 pounds is ~~= to 21 grams imbalance and tires should all be maintained at 5 grams or less ~~= 7 pounds as shown on hunter.

The pounds are the upward force on suspension as the hardest stiffest spot rotates around on the road. With a 146 pound front spring that 7 pounds pushes up 0.05" and sets up the oscillation........like hitting a tiny bump every 6 feet depending on speed.

Some tires/wheels have 2 or more stiff or out of round spots.

http://128.242.141.111/pub/technical/in ... ec...4.cfm

Infiniti uses 14 pounds as acceptable limit, I feel this is too much and is quite feelable therefore recommend 7 pound limit............depends on shock stiffness.

[gloucester Q]

would it be crazy of me to take two separate sets of q wheels in and ask a tire installer to find the 4 truest of the bunch and chuck the others for my next set of tires? i have a set that looks to be in pretty good shape (originally slated for winter tires), and then there's the set on the car, which, from driving around these things that pass as roads up here in mass, i'm sure are taking a beating. i assume a shop would have no problem figuring out which wheels are truer?

rover, where did you go and what michelins did you put on?

[rover3l]

I went to Roux's garage on West Street in Berlin. It is a father and son business and I am very impressed with their approach. They take a real interest in their work and for example in changing my tires the took about 100 digital photographs of my suspension, brakes etc so when I arrived latter he sat me down and was talking about the active system. This was in part related to me asking them to diagnose a rattle noise. They are apparently a 5 star garage what ever that means in MA. It is a country garage but immaculate inside with all the latest equipment. His Hunter machine was the latest generation

The Michelins were 235 60's H rated XGT4's drop shipped to Roux's garage by Tire Rack. Delivery was 2 days from their NJ wharehouse. I chose these tires because they have a load rating over 1600. I also have a set of Pirelli Wintersports on steel rims for winter use

[rover3l]

Here is what the print out shows in detail

Hunter GSP9700 Road Force Measurement System Vehicle Summary

For least pull there is a diagram of the 4 wheels with the following data:

the front left wheel shows 16lbs and have a number 3 with a star symbol in a 5 sided box

right front is 23lbs with a number 4left rear is 10lbs with a number 2 right rear is 15 lbs with a number 1

At the top of the diagram is a heading which says 0lbs net pull.

Below there is a table showing alternative placements and the effect on net pull

Then the is a second diagaram labelled for least vibration showing the same road force numbers but now the tires in different positions. The overall net pull is 1lb

It seems then to me that he has simply mounted the tires as is and these are the road force measurements that resulted?

The road force numbers seem too high if he has balanced the wheels??

[Q45tech]

Around ATL they charge $20-25 per tire to test and correct. Takes time to test, think about it, read and study up then demount and rotate relative tire wheel positions to achieve low results.Easy to spend 20 minutes per tire and more if you are not a mental giant and can do the vector algebra in your head.

Just mounting a single tire on a wheel is a $7-$10 each proposition

A good cheap proceedure is to spin balance the wheels alone without the tires........new wheels will probably require less than 5 grams on the inside and less than 10 grams on the outside flange. The lower the better.There is correlation between what a spin balancer shows and the radial force effects but it is not absolute. But with Michelin it is almost always the wheels as EVERY tire is tested before it leave the factory.

Another necessary thing is to drive on the tires for 250-500 miles to exercise and stablize them.You get tremendous variations in balance in the first 50, 100, 150, 200 miles.

Pay them to correct match mount the tires and wheels

Don't worry about 1-2 net pull get the radial forces below 10 pounds all around.