One day while driving down the highway I noticed that I was getting a resonating shudder in the steering wheel about every 5 seconds. New tires were definitely in order and I decided to go the full gamut and have the rims checked out as well. So I loaded up the wheels on a pallet and carted them to the refurbishing shop. Note the 3 different tire manufacturers from the PO.

The refurbishing shop that I used does the wheel setup for some of the teams that race down here at the Homestead Speedway, so they really know their stuff. You can see here that the tires were safely removed from the rims using state of the art equipment from Hunter Engineering. This is the sort of equipment you want used on those expensive low-profile tires and rims.

With the tires were removed, the BBS rims were checked for runout on a Hunter GSP 9700 - more on runout and other nasty stuff later. It was determined that 3 of my 4 rims were either bent or out of round, so I opted to have them all refurbished.

Once my special order Yokohamas finally arrived, I picked them up from Sabal Chase tire and transported them over to the refurb shop for speed mounting and balancing on the now refurbished rims. Though the front tires sizes were still common, the rear tires were not being stocked anywhere, thus the need to order out. Yokohama's AVS Intermediates were the only complete tire set that I could find to match the sizes I needed, 195/60VR15's for the front and 235/60VR15's for the rear.

With the new tires mounted, the technician sets up the assembly for mount matching to check for runout and excessive wheel force variation on the GSP 9700; this will determine whether the rim has been properly refurbished to within acceptable tolerances, as well as to whether the tire is defective. The system also shows whether any adjustments can be made to better match the tire to the rim to further reduce vibration.

After running a simulated road-test on the tire, the computer display below shows the diagnosis of the wheel assembly.

During this quick tire education, I learned that runout is when a tire or rim is out of round when rolling and is frequently caused by a bent rim or uneven tire wear. In this case our newly refurbished rim now passes the runout test and won't be the cause of any vibration. I also learned that force variation in a wheel assembly can yield excessive vibration and is usually caused by wheel runout or uneven tread or sidewall stiffness in the tire. Since no two tires are ever manufactured alike and are never uniform in flexibility or roundness, it's possible for a new tire to be unusable or defective. However, most tires are within an acceptable spec and can be fine tuned to the rim as to reduce further reduce any force variation, as was the case with my tires.

In this particular rim and tire combination, the computer mount match determined that some additional reduction in the force variation could be attained by matching the high point or stiff spot in the tire with the lowest spot in the rim. This offset or counter-balance of imperfections makes the wheel rounder when rolling. The computer indicates to the tech where the rim and the tire should be matched and each of these points are marked with a yellow chalk line.

The assembly is now moved back over to the tire changer that will spin the rim while keeping the tire stationary in order to correctly line up the yellow chalk marks.

Note how the yellow chalk marks on the tire and rim are now properly lined up according to computer determined optimal settings. Tire fine-tuning 101.

Finally, the tire is dynamically balanced - this eliminates both up-and-down as well as side-to-side vibration. Most tire stores only do static balancing which doesn't take care of any side-to-side imbalance and the difference can be noticeable at speed. As you can see here, the correct set of weights are pressed on the inside of the rim, and are positioned closer to the inside for this particular wheel. The weights have a sticky backing once the paper strip is peeled away, so no additional adhesives are required.

Freshly mounted new Yokohama AVS's on re-minted BBS rims - life is good!

The new tires and refurbished wheels really made a world of difference in handling and performance.

If you're interested in finding out if there are shops in your neighborhood using this type of equipment, click here.