The one-piece rim is commonly used today and has integral design features regardless of the material it is made from. The wheel rim must allow the tire to seal and maintain pressure while allowing easy mounting and removal. The well enables tire removal and replacement by allowing one bead to stretch into it. The flange prevents the tire from coming off the rim. Some rims have added safety ridges in the taper to stop tire detachment if a puncture occurs.

1. Wheels and Tyres
Page 2

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.

3. 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.

4. Label the wheel rim below
Well
Taper
Valve
Flange

5. 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.

6. What is the purpose of the flange?
• The flange is there to stop the tyre from
coming off the rim

7. What is the name given to this type
of valve?
• It is known as a Schrader valve

9. What unit of measurement is the
wheel rim diameter most commonly
measured in?
• Rim diameter is commonly measured in
inches

10. What is the measurement shown
by the letter J?
• The letter ‘J’ refers to the rim flange height

11. What is the unit of measurement
that is used to measure tyre width?
• Tyre width is commonly measured in
millimeters

12. 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.

13. Add them to the drawing of the rim
opposite.

14. 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?

15. 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.