Tread Wear

IRREGULAR AND/OR PREMATURE WEAR





Irregular and premature tire wear has many causes. Some of them are: incorrect inflation pressures, lack of regular rotation, driving habits, or improper alignment. If wheel alignment is reset due to tire wear condition, always reset toe as close to zero degrees as the specification allows.

If the following conditions are noted, rotate the tires:
^ Front tire wear is different from rear.
^ Uneven wear exists across the tread of any tire.
^ Left and right front tire wear is unequal.
^ Left and right rear tire wear is unequal.
^ Check wheel alignment if the following conditions are noted:
- Left and right side tire wear is unequal.
- Wear is uneven across the tread of any tire.
- Tire treads have a scuffed appearance with "feather" edges on one side of the tread ribs or blocks.

TREAD WEAR INDICATORS





The original equipment tires have built-in tread wear indicators to show when the tires should be replaced. These indicators will appear as 12.7 mm (1/2 inch) wide bands when the tire tread depth becomes 1.6 mm (1/16 of an inch). When the indicators appear in 2 or more grooves at 3 locations, replace the tire.

RADIAL TIRE WADDLE
Waddle is side-to-side movement at the front and/or rear of the vehicle. Waddle is most noticeable at low speed, about 8 to 48 km/h (5 to 30 mph). It may also appear as ride roughness at 80 to 113 km/h (50 to 70 mph).

The vehicle can be road tested to see which end of the vehicle has the faulty tire. The following wheel/tire substitution procedure may be used to isolate the tire and wheel assembly which is causing the "waddle":
1. Drive the vehicle to determine if the waddle is coming from the front or rear.
2. Install tire/wheel assemblies known to be good (from a similar vehicle) in place of those on the end of the vehicle which is waddling. If the waddle cannot be isolated to front or rear, start with the rear tires.
3. Road test again. If improvement is noted, install the original tire/wheel assemblies one at a time until the faulty tire is found. If no improvement is noted, install tires known to be good in place of all four. Then, install the originals one at a time until the faulty tire is found.

Waddle can usually be related to excessive lateral runout of the tire or wheel. Use a dial indicator on the tire's sidewall and on the rim's flange to determine if excessive lateral runout exists.

RADIAL TIRE LEAD





"Lead" is the deviation of the vehicle from a straight path on a level road with no pressure on the steering wheel.

Lead is usually caused by:
^ Improper wheel alignment.
^ Uneven brake drag.
^ Lateral tire forces due to tire construction.

The way in which a tire is built can produce lead in a vehicle. An example of this is placement of the belt. Off-center belts on radial tires can cause the tire to develop a side force while rolling straight down the road. If one side of the tire has a slightly larger diameter than the other, the tire will tend to roll to the side with the smaller diameter. This will develop a side force which can produce lead.

Part of the lead diagnosis procedure is different from the proper tire rotation pattern shown in the owner's manual. If a medium-to-high mileage tire is moved to the other side of the vehicle, a temporary increase in tire noise or tire roughness may occur. Tire noise and/or roughness should diminish within a short time as the tire wears. REAR TIRES WILL NOT CAUSE LEAD.