Demounting And Mounting Wheels With Low Profile, Uhp Or Run Flat Tyres; Preliminary Checks - Nussbaum TC 450 Manual De Instrucciones

ENGLISH • Instructions manual

10.4 DEMOUNTING AND MOUNTING WHEELS WITH LOW PROFILE, UHP OR RUN FLAT TYRES

Nussbaum has developed this procedure to provide operators in the sector with correct working procedures for UHP and reinforced
side run-flat tyres.
Thorough studies have revealed that an incorrect working procedure causes often irreparable damage to tyres during mounting and
demounting, putting the safety of the vehicle itself at risk.
Low-profile tyres are tyres having a ratio between their height (H) and cross-section width (C) of less than 1; e.g. the 60 low-profile
series has a H/C ratio of 0.6.
Ultra High Performance (UHP) tyres have a height-width ratio of 45% or less, and a velocity index of V or above.
Run-Flat tyres are tyres which still allow the vehicle to travel for a specified distance at a specified speed, which varies from constructor
to constructor, even if no longer pressurised. This is achieved by using a different rubber blend and a reinforced structure, which enable
the shoulder of the tyre to support the weight of the car even when the pressure inside it has fallen to zero, allowing the vehicle's driver to
reach the nearest service centre in safety.
At present, there are two different types of run-flat tyres on the market: the reinforced sidewall type, also known as self-supporting
tyres, and the type with an internal support may be made from plastic (Pax-System) or metal (Support-Ring).
These tyres' characteristics make mounting operations more problematical, and it is extremely important not to
cause damage during mounting and demounting operations, as this may reduce the vehicle's safety level.
The TC 450 - Liga C 270 tyre changer can operate safely on all self-supporting Run Flat tyres.
For other types of run-flat tyre, refer to specific instructions supplied with the special
accessories.
The mounting and demounting procedure is the same for both self-supporting run-flat, and
low profile and UHP tyres.
WARNING: It is essential to follow the instructions closely to
avoid irreparable damage to the tyre, which might put the
vehicle's safety at risk.
WARNING: Figs. M1 and M2 show the points with the highest risk of damage during demount-
ing (M1) and mounting (M2):
these are the traction points where the tyre is very taut against the edge of the rim.

PRELIMINARY CHECKS

Comply with work-place safety regulations.
All operators must have suitable clothing, gloves, safety footwear, etc.
The tyre and rim must be cleaned thoroughly.
Identify the parts correctly: both the tyre and the rim.
Rims have their diameter, width, Hump number, etc. data stamped on their surfaces.
E.g. a marking 7.5Jx16H2
7.5 Indicates the nominal width of the rim
J
is the size of the flange
16 is the nominal diameter of the rim
H2 indicates a double hump
43
M/1
M/2
TC 450 - Liga C 270