Blossary – tire information

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tire information

Most Ford car and light truck tires carry a P-metric designation such as P185/70R14 or an LT-metric designation such as LT235/70R16. In the charts below, the alphabetical or metric and load range letters used are obtained from Tire and Rim Association Standard Tables. P-metric Steel-belted Radial-ply Tires All Ford cars and most light trucks have P-metric steel-belted radial-ply tires as standard equipment. They are designed in accordance with nationally accepted dimensional standards. Benefits include:

Improved fuel economy through increased inflation pressure (up to 35 psi; 44 psi for some light trucks)

Tread compounds designed for reduced rolling resistance LT-metric Steel-belted Radial Tires

Available with both all-season and all-terrain tread patterns for greater versatility

Designed to support larger vehicles and heavier loads Medium-Duty Truck Tires used on Ford medium-duty trucks (F-650/F-750 and Ford LCF) are of a radial-ply design. They fall into several classes of service conditions:

Over-the-road (highway) tires are used on paved surfaces for local and/or long distance runs

Mixed service tires are for use on a variety of surfaces such as pavement, gravel, dirt or other unpaved surfaces

All-position tires have treads that are suitable for general over-the-road operation

Steering axle tires usually feature circumferential grooves that equalize pressure across the tread face

Drive axle tires have deep treads and block-type patterns for extra traction All-season Tires Most Ford vehicles use all-season tires with a wraparound block-type tread design that offers the following benefits:

May be used year-round as standard passenger car or light truck tires Tread compounds and tire construction used with the all-season tires are formulated to convert less energy to heat when flexing compared to previous compounds. This helps reduce rolling resistance compared to previously designed steel-belted radial-ply tires. All-terrain Tires

All-terrain tires are available on several light trucks, primarily on 4x4 models. As their name indicates, all-terrain tires are designed for both on- and off-road use over a variety of surfaces

Generally, they have a deeper, wider tread design than all-season tires for better gripping on a variety of surfaces Aspect Ratio

As an example, a tire with an aspect ratio of 75 would have a section height that is 75 percent of the tire’s width

Lower aspect ratio reflects a shorter, wider tire that offers greater contact with the road. Dual Spacing Distance between the center lines of both tires on a dual-rear setup. Flotation Tires

Usual applications are for off-road operation where soft sand, mud, marshy or snowy conditions are typical Offset

On dual wheels, the distance from the center of the rim midway between the flanges to the outer mounting face of the wheel

On single wheels, this is the distance from the center of the rim to the wheel mounting surface Performance Tires, All-season

Performance tires generally have aggressive tread designs and are distinguished by large, solid tread blocks separated by open channels to promote water drainage and prevent hydroplaning

A key benefit of performance tires is optimized steering response and adhesion during acceleration, braking and cornering, usually with some small penalty in ride harshness and tread noise Ply Rating (PR), Load Range (B), Load Index/Speed Designation (97V) or Standard Load Rating (SL or XL)

Ply rating is a standard unit of tire casing strength, based on the strength of cord plies

It is an index of tire strength and does not necessarily represent the number of cord plies in the tire

P-metric passenger-type tires are offered with a standard load rating (SL — up to 35 psi) or extra load rating(XL — up to 41 psi)Radial-Ply Tires Type of tire that has one or more rubberized plies of cords running from bead to bead at right angles to the tread and parallel to each other, plus two or more plies of reinforced belts that encircle the tire under the tread. Rim Width Distance between the inside surfaces of the rim flanges. Speed Designations Tires are laboratory wheel-tested at specified load and inflation pressure for the speed designation. R-rated tires are specified for speeds up to and including 106 mph S-rated tires are specified for speeds up to and including 112 mph T-rated tires are specified for speeds up to and including 118 mph H-rated tires are specified for speeds up to and including 130 mph V-rated tires are specified for speeds up to and including 149 mph Z-rated tires are specified for speeds over 149 mph NOTE: Speed designations are for reference only. Actual speed capability of tires may change in vehicle applications. Tire Clearance to Vehicle Distance between the tire sidewall or tread and the nearest part of the vehicle’s chassis, suspension or body. Tire Loaded Radius

Distance from the center of the wheel to the road with tire loaded to rated capacity

Static radius applied when vehicle is at rest Tire Revolutions per Mile Term used for the number of times the tire revolves when traveling one mile. Tire Section Width Maximum outer width of an inflated new tire from sidewall to sidewall, exclusive of ribs, bars, decorations, etc. Track Width Lateral distance between the centers of the front or rear tires. Unidirectional Tires Tread pattern designed for rotation in the direction indicated on the sidewall and used in some performance tire designs, e.g., Goodyear Eagle VR60 tires.