Inspection
Tread wear indicator bars will appear on Pirelli Diablo T tire tread surfaces when 1/32 in. (0.8 mm) or less of tire tread remains. Always replace tires before the tread wear indicator bars appear on the surface of the tire.
See Figure 1. The location of tread wear indicator bars are identified by 'TWI' markings on the tire sidewalls.
When To Replace Tires
New tires are needed if any of the following conditions exist:
  1. Tread wear indicator bars become visible on the tread surfaces.
  2. Tire cords or fabric become visible through cracked sidewalls, snags, or deep cuts.
  3. A bump, bulge, or split in the tire.
  4. Puncture, cut or other damage to the tire that cannot be repaired.
1Tread wear indicator bar
2Sidewall 'TWI' marking
Figure 1. Tread Wear Indicator: Pirelli Diablo T