Tyre guide/information

[WABIT]

Tyre Reference Guide


This glossary of frequently used tyre-related terms is for your reference. When ordering from us you may be asked about certain aspects of your tyres or wheels that are covered on this page. You will also see some of these terms in the specifications charts located throughout this catalogue. Please note that all measurements in this catalogue are listed in inches.

Aspect Ratio/Series Number - the height and width relationship of the tyre. This number is determined by dividing a tyres section height by its section width. For example: the section height of a 215/70-14 is 70% of the section width, that being 215.

Section Height - the tyres section measured from the rim seat to the outer tread surface of an inflated tyre.

Cross Section - the linear distance be-tween the exteriors of the sidewalls of an inflated tyre.

Bead - the specialised area of the tyre designed to mate with the rim flange. Reinforced with steel cable on straight side tyres; reinforced with fabric on clincher tyres.

Bead Seat - the horizontal surface of the rim where the bottom of the tyre bead contacts the rim.

Rim Diameter - the diameter of the rim at the bead seat. The most accurate method to determine the diameter is to measure the circumference of the rim at the bead seat and divide by TT (3.14).

Tread Width - the portion of the tread design that comes in contact with the road surface

Overall Diameter - the linear distance between the exterior tread surface from the ground to the top of the tyre

Load Capacity - the maximum weight a tyre can support at its maximum in-flation pressure (eg. 1360 Ibs @ 32 psi)

Clincher (beaded edge) rims/tyres - the rims are usually one piece. They can be permanently mounted to the wood felloe or in some cases de- mounted from the wheel itself. The clincher rim itself has a curved bead edge that forms a cavity or clinch; the clincher tyre bead is designed to fit into this cavity. Clincher tyres are held on by air pressure requiring a minimum of 50 psi and can only be mounted on clincher rims.

Standard Detachable rim - Early style rim that is permanently mounted to the wheel. This tyre can be taken off the rim by removing the side ring.

Detachable/demountable rim - Early style rim that can be demounted or re- moved from the wheel. These rims are usually mounted to the wheel by clamps or rings. These rings can be "solid" with removable side rings or they can be "split rims".

Traditional Whitewall Widths
Pre-1954 - 3" whitewall or more
'54 thru '56 - 2 1/2" - 2 11/16" '57
thru '61 - 2 1/4" - 2 1/2" '62
thru '64 - 1" whitewall or less

Speed Ratings
P..........93mph..........150km/h
S..........112mph........180km/h
T..........118mph........190km/h
H..........130mph........210km/h
V..........149mph........240km/h
Z........+149mph......+240km/h

[rayray086]

Also check out carbibles's Wheel & Tyre guide (carbibles.com)

[Peter Jones]

Another piece of the puzzle, Load ratings are the number that preceeds the speed rating eg 82H

[perry_oiledwheel]

Speed Ratings
P..........93mph..........150km/h
S..........112mph........180km/h
T..........118mph........190km/h
H..........130mph........210km/h
V..........149mph........240km/h
Z........+149mph......+240km/h

[Manaz]

Where does the "W" speed rating specified by the factory for my tyres fit in?

[Peter Jones]

W 270 KM/H
Y 300 KM/H
VR >210 KM/H
ZR >240 KM/H

(From Michelin site LINK)

Pete

[Manaz]

W 270 KM/H
Y 300 KM/H
VR >210 KM/H
ZR >240 KM/H

(From Michelin site LINK)

Pete

Just as well - 240km/h+ wasn't fast enough for me!



But seriously - does that mean that V rated tyres (240km/h+) are potentially higher rated than W (270km/h)?

[Transporter]

There are many tyre size calculators on net, but this one has a nice graphics.

http://www.rims-n-tires.com/rt_specs.jsp

[Lima]

1010tires also has a couple of good calculators...

http://www.1010tires.com/TireSizeCalculator.asp
http://www.1010tires.com/WheelOffsetCalculator.asp

[Sentinel]

Here are some illustrations showing different types of tyre wear, and their likely causes.