COMPRESSION RIM GROOVING--AN OBJECTIVE MEASUREMENT TECHNIQUE

By

Troy Cottles

Presented at the HIFI Tire Tech Conference, Houston, TX

August 13, 2010

Compression Rim Grooving- Background:

Prior studies Methodology Subjectivity Precision

Compression Rim Grooving- Background:

Objective Measurement Technique:

Compression Rim Grooving- Background:

Test Protocol:

CONTROL REDUCED-INFLATIONInflation Pressure: 30 PSI 21 PSILoad: 890 lbs 890 lbsRim: 14 X 5.5 14 X 5.5Speed: 75 mph 75 mphDuration: 40,000 miles 40, 000 miles

Compression Rim Grooving- Background:

Test Tires: Yokohama Aspec A300, H-rated, FD3505 Bridgestone B700AQ, T-rated, 2R3605 Dunlop Sp Sport LM701, H-rated, EU4005 Dayton Quadra SE, S-rated, HY2105 Firestone FR690, S-rated, W22805 Uniroyal Tiger Paw, S-rated, K41605 Hankook Radial H714, S-rated, 1G1405 Michelin Symmetry, S-rated, HN1204 Toyo Spectrum, S-rated, 9T5004 Federal Supersteel 735, T-rated, 2E4905 Cooper Lifeliner SLE, T-rated, U94305 Dunlop SP20FE, S-rated, M63605

Compression Rim Grooving- Control Tires:

New Tire Photos-Tire #28 Uniroyal Tiger Paw

Compression Rim Grooving- Control Tires:

New Tire Laser Profile-Tire #28 Uniroyal Tiger Paw

Compression Rim Grooving- Control Tires:

Tire Photos After Test-Tire #28 Uniroyal Tiger Paw

Compression Rim Grooving- Control Tires:

Laser Overlays-Tire #28 Uniroyal Tiger Paw

Compression Rim Grooving- Conclusions: Tire designers calculate bead compression values when tires are being designed and developed.

Without bead compression the tire would not fit properly to the rim, possibly lose air, slip on the rim or de-bead.

Previous studies have concluded that rim grooves are produced by under-inflated operation.  This study demonstrates that rim grooves can be produced even under proper inflation and

load conditions. Twelve control tires of different brands, manufacturing facilities, tire constructions, rubber

compounds and properties, amounts of rubber gauge in the bead flange area, and various bead contour designs were operated on laboratory drum machines under the same loads, inflation pressures, and speeds where the variable of how often someone might check their tire pressure on their personal vehicle was eliminated from consideration. Given many of the mentioned differences in the control tires, the rim grooves generated varied from just perceptible to clearly-defined as to rim groove depth.

The notion that the mere presence of a rim groove could serve as the sole indicator of tire under-inflated operation for a consumer is itself not useful or practical, since the tire would have to be removed from the rim in order to view the area in question.

The notion that the mere presence of a rim groove could serve as the sole indicator of tire under-inflated operation for a proper forensic analysis is likewise unreliable as an indicia of that condition given the range of rim grooves presented in the control tires in this test.

It is possible to evaluate rim grooves (and other contour changes to tires) through the objective, high-precision, non-contacting, quantifiable means of laser scan imaging as demonstrated in this study.