Tire Education

Tire Focus Jun, 4 2018

TIRE FOCUS

Why tires wear abnormally:

Factors affected by tire wear:

Drivability and stability
Ride quality and smoothness

Heat radiation transferability
Performance in rain/snow

Tire wear indication:

Vehicle Type	Ordinary	Highway
Passenger vehicle	1.6 mm	1.6 mm
Small sized truck	1.6 mm	2.4 mm
Truck or bus	1.6 mm	3.2 mm

Passenger vehicle Ordinary – Highway

1.6 mm – 1.6 mm

Small sized truck Ordinary – Highway

1.6 mm – 2.4 mm

Truck or bus Ordinary – Highway

1.6 mm – 3.2 mm

How to read the tire specification code:

A Passenger car tire in P-metric sizes. Tire sizes without the “P” may also be made for passenger cars, but they are “European” metric sizes and may have different load ratings or speed ratings than P-metric tires.

Tire width, measured from sidewall to sidewall in millimetres. This information is used to determine the width of the rim that the tire can be mounted on.

Aspect ratio, indicating the height of the tire as a percentage of the width. In this case, the tire would be 94 mm (235 x 40%). High-performance tires usually have a lower aspect ratio (below 55%) than other tires because lower ratios provide better stability. When turning, cars generate lateral forces that the tires must resist. Lower profile tires have shorter, stiffer sidewalls so they resist cornering forces better.

Radial construction, indicating that the plies that strengthen and reinforce the tires radiate out at a 90 degree angle from the centre of the tire. This improves fuel economy in comparison to bias-ply tires, whose plies are at a 60% angle.

The diameter, in inches, of the wheel that this tire can be mounted on, regardless of whether the tire is mounted on a steel or alloy wheel.

The Load Index is a standard that applies to all tire manufacturers, classifying tires according to their load-carrying capacity, or how much weight they can support at maximum air pressure. In this case, a load index of 99 corresponds with 775 kg. Load indexes of the tires used on passenger cars and light trucks usually range from 80 to 110, corresponding with weight capacities between 450 and 1060 kg.

The Speed Rating indicator, established to match the speed capability of tires with the top speed capability of the vehicles to which they are applied. The letter corresponds with a maximum speed rating, in kilometres per hour. Popular ratings on Lexus vehicles include: S-180km/h, T-190km/h, H-210km/h, V-240km/h. Despite the capability of the tires to operate at high speeds, Lexus vehicles should not be operated in excess of legal speed limits.

235

Tire width, measured from sidewall to sidewall in millimetres. This information is used to determine the width of the rim that the tire can be mounted on.

Aspect ratio, indicating the height of the tire as a percentage of the width. In this case, the tire would be 94mm (235 x 40%). High performance tires usually have a lower aspect ratio (below 55%) than other tires because lower ratios provide better stability. When turning, cars generate lateral forces that the tires must resist. Lower profile tires have shorter, stiffer sidewalls so they resist cornering forces better.

Radial construction, indicating that the plies that strengthen and reinforce the tires radiate out at a 90 degree angle from the centre of the tire. This improves fuel economy in comparison to bias-ply tires, whose plies are at 60% angle.