Wheels and Tyres

Page 2

A common rim in use today is

the one piece rim. The one

piece rim has design features

made as part of its integral

design regardless of the

material it is made from.

The wheel has to allow the tyre

to seal against it to allow the

tyre pressure to be maintained

and it has to allow easy fitment

and removal of the tyre.

Label the wheel rim below

Well

Valve

Taper

Flange

What is the purpose of the well?

• The well is the deep part in the middle of

the rim, it is there to enable the removal

and refit of the tyre.

• The bead of the tyre can’t stretch over the

flange so one side of the bead is pushed

into the well to allow the tyre to be

removed.

What is the purpose of the flange?

• The flange is there to stop the tyre from

coming off the rim

What is the name given to this type

of valve?

• It is known as a Schrader valve

What unit of measurement is the

wheel rim diameter most commonly

measured in?

• Rim diameter is commonly measured in

inches

What is the measurement shown

by the letter J?

• The letter ‘J’ refers to the rim flange height

What is the unit of measurement

that is used to measure tyre width?

• Tyre width is commonly measured in

millimeters

Some manufacturers now have

an extra safety design built into

wheel rims, what are they?

• Some rims have ridges made as part of

the taper

• They are there for safety, they stop the

tyre coming off of the rim in the event of a

puncture.

Add them to the drawing of the rim

opposite.

Questions

• What is the purpose of the well of the

wheel rim?

• What is the purpose of the taper?

• What is the rim diameter measured in?

• What is tyre width measured in?

• What is the difference between a normal

rim and a safety rim?

Answers

• To allow the tyre to be removed and refitted

• To allow the tyre bead to seal tightly against the rim

• Inches

• Millimeters

• Safety rims have extra ridges in the taper part of the rim to stop the tyre from coming off of the rim in the event of a puncture occurring whilst driving.