Tech Talk

Sorry folks but a lot of information to pass on in this one, but its important to your safety and wallet….so here we go.

What do the following have in common?

Coats, Entire Catalog, Hunter, National Auto Tools, Accu-Turn, CEMB USA, RELS, Corgi, Ranger, and American Products?

Give up; they all make equipment to change your rim and tires.  Doesn’t seem to be a monopoly for sure.  In this month tech talk let’s take a look at the problems and potential dangers to your car and expensive rims which can be caused by improper use of these machines. 

Today’s low profile and run flat tires create a very challenging problem for the makers of this equipment.  In the day of old steel rims, steel rim on steel changer was never a problem for the removal or installation of a tire on the rim.  However today, the softer and exotic metals such as magnesium and aluminum are easily marred and damaged by improper use of these machines.  Add to that the lower profile tire with stiffer, much stiffer side walls and you have the makings for a disaster to your car.  These newer tires do not stretch and their softer wheel metal will give to the much harder steel clamps and bars used to remove the tire.  So what is the answer….proper training and proper use of the machinery.  Don’t be afraid to ask to see the shops machinery and ask the manager if the 18 year old high school drop out has trained on and been monitored removing tires from $1000 - $4000 dollars of expensive rims?  Better know what the liability is before you discover the hard way…right.   Today’s equipment has advanced to keep up with the larger rim sizes and low profile tires.  If old Billy Bob on the corner did your dad’s 1947 Pontiac and is still using he same old reliable tire changer, I have one word of advice…RUN…rather drive away and drive fast.

If you look at the anatomy of the rim, it is in effect a barrel with a lip, tip and bottom.  In order to turn the rim and “pop” the tire over the lip of the rim the wheel must be held securely to the clamping device on the machine, because the machine will rotate your rim on the machine and use pry bars to pull the tire over the rim lip.  The machine clamps in two ways, inside the wheel “barrel” or clamp to the rim lip on the back bottom side (not the side we see).  The proper way for all custom and exotic wheels is the clamp the lips of the rim from the back under side with the good wheel face facing upward.  If anyone tries to tell you they clamp from the inside using boots or plastic covers on the steel teeth all the time, I suggest you go to another installer.  If clamped from the inside without protective boots, the wheel could slip somewhat while being turned and the STEEL teeth will cut into you wheels.  Most of the better equipment used by installers contain warning to the installer to clamp from the outside lip.  Once securely held in place, ask and or observe if any of the other parts used to remove the tire will allow machinery metal to contact wheel metal (you don’t want this, “trust me” doesn’t work).  Insist that the proper plastic or Teflon protective sleeves are utilized on ALL devices which may touch your rim.  The better machines and better installers will never leave a mark or argue with you, because they already know.  If you want to remove a good set of run flats or low profile tires to put on another set of new shiny wheels ensure that the side walls will not be damaged, as this can happen.  Better know up front if the tire center will pay up.  Also before you let them touch your wheels. Take a dry erase pen and with the manager go over your wheels and mark any scratches.  It is so easy to say “We didn’t do that it already existed”.  Without these simple precautions, kiss several thousands of dollars in perfect rims goodbye. 

Once mounted your new expensive tires and rims are mounted you will need them balanced.  Think all balancing is the same…I think not.  For the proper mounting of tires and wheels not purchased as a pre-mounted Tire & Wheel Package, be sure to observe some basic precautions:

• Mounting and balancing should be done by a professional, using equipment designed for the job (there goes that proper equipment theme again)
• Both tire beads are securely mounted
• The wheel is not bent or damaged (you can have a run out done before mounting)
• There is no buildup of dirt between the hub and the wheel (ya, how many of you mud run your Corvette)
• All of the lugs have been properly torqued (about 100lbs for a C-6, but check you owners manual)
• The wheel is securely seated on the hub

The definition of balance is the uniform distribution of mass about an axis of rotation, where the center of gravity is in the same location as the center of rotation (impressive yes?).  In English, that would translate to.....A balanced tire is when the mass of the tire, when mounted on its wheel and the car's axle, is uniformly distributed around the axle. Even easier yet, how about.....there are no heavy spots.

Balanced tires can be the difference between a good or bad driving experience. Some cars (and drivers) are more sensitive to an out of balance tire than others, but no one is happy with a vibration (especially anal retentive Vette drivers…..hummm…know any).

An out of balance tire can adversely affect ride quality, shorten the life of your tires, bearings, shocks and other suspension components. If you have a vibration that is dependent on speed, and usually becomes noticeable around 40-45 mph and increases as your speed increases, it's probably balance related. The other primary cause of vibrations is that the tire and wheel assembly isn't perfectly round. Face it, if we go out far enough past the decimal point, nothing is perfectly round. This includes your wheels and tires. The problem is when the high spot on the tire, and the high spot on the wheel end up being matched to each other. This effectively doubles the amount of "hop" or runout. If re-balancing doesn't cure the vibration problem, have your professional installer check the runout of the tire. If there is a "hop", many times the problem can be fixed by simply rotating the tire on the wheel slightly. The technician should loosen the tire on the wheel, and turn it 180 degrees, and reinflate the tire after relubricating the bead. The runout should be significantly reduced or eliminated, and if it's not, try it again, but this time rotate only 90 degrees, and if that doesn't work, try 180 degrees on the third try (o ya, three tries to scratch my rims…stay tuned to a better approach). Done this way, the high spot on the tire has been tried at each quarter of the wheel. At one of those points, the tire should be good and round. At that point, rebalance the tire, and go for a test drive. If the vibration persists, the problem is either in the tire, or elsewhere in the vehicle.

High speed tires have color dots on them to mark the heavy spot which is supposed to mounted opposite the valve stem.  Want to impress the installer, ask him what the dot is for?

Now, isn’t there a machine to check this out before it goes on my car….yes there is.  Ask to have your tires Road Force Balanced (RFB).  Without RFB, you can actually balance an out of round or flat spot tire (it will still vibrate).  The RFB process actually spins your tire and places a pressure sensitive drum against the tire while it spins.  I won’t bore you with the details, but it measure the amount of pressure required to make the tire run true (it pushed into the tire as it spins).  The more force to “eliminate” the wobble, the more out of round or “flat spot” the tire has.  If the amount of force exceeds the limit, (about 10-15 lbs) the tire is defective.  Get a new one.  The installer can try to rotate it but I would turn the tire in myself.

I talked to the new Discount Tire Store, and they can and will give you the best deal in town.  PS, they have all the best equipment and insist with the manager only the best installer mess with your car.  Byron Tire also has the right equipment.  I think John Hoopes used them once.  Kubia will send you to Byron if you have run flats or really low profile tires.  So be careful who you pick, it’s your wallet.

Wow, a lot on information this month, but it could be your life or at least a set of rims in the balance.  

Tech Talk Dan

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