Why regroove a tyre

The aim of regrooving

If carried out in accordance with our recommendations, regrooving extends the tyre’s grip potential, thereby reducing it’s cost.

Regrooved tyres may be mounted either front or rear axles of a vehicle.

Regrooved tyres may be retreaded, and retreaded tyres may be regrooved.

This operation should only be used on truck or crane tyres.

Tyre-regrooving is recommended by the international standards (ETRTO, AFMOR,TRA, etc.) because of improved safety and reduction in cost it provides.

Savings

Regrooving significantly increases tyre wear life (by up to 20% in some cases). It is not detrimental to retreading in any way. Regrooving also brings fuel savings because the tyre’s useful life is extended into a period where its rolling resistance is usually the lowest.

Recommendation

Regrooving must be performed when there are still 2 to 3 mm of remaining tread depth (dimension p).

Regrooving at 2 to 3mm remaining pattern ensures that:

• the tread pattern can be reproduced without too much difficulty
• the depth of regrooving can be adjusted so that there is always at least 2 mm of rubber remaining between the base of the tread groove
  and the crown plies (fig. 1).

Regrooving method

Equipment required

• A tyre regroover
• Rounded blades Use only R4 rounded blades (with a width of 11 mm to 14 mm) or R5 rounded blades (with a width of 14 mm to 17 mm).
• Blade

Regrooving dimensions

Refer to the brochure on regrooving Michelin CRANE tyres.

A regrooving depth-indicator, located in the wear indicator, allows optimum adjustment of blade height.

For obvious safety reasons, we recommend probing the tread band where it is most worn to gauge the depth of rubber remaining above the crown plies.

In all events, leave 2 mm of rubber between the base of the tread groove and the crown plies (fig. 2).

Regrooving Chart

Refer to the brochure on regrooving Michelin CRANE tyres.

Precautions to be observed

The following safety rules must be followed for the protection of the operator, tyres and the environment.

Precautions for operators

During tyre handling and regrooving operations, gloves, protective glasses and safety shoes should be worn.

Making the tyre safe

During tyre handling and regrooving operations, the operator must check that the tyre is secure, and made safe if necessary, at least each time the tyre is turned around or over.

Recommendation:

the tyre should be fixed to prevent it from rolling or falling over.

Mandatory demounting

All regrooving operations must be done on demounted tyres.

IMPORTANT RECOMMENDATIONS
Excessive regrooving may:

• cause damage leading to the premature destruction of the tyre;
• possibly make unsuitable for retreading;
• expose the crown plies at the base of the tread groove, which is prohibited the law in most countries.

Regrooving is not advisable if the tyre’s tread presents significant signs of having been used on damaging surfaces: large numbers of cuts, pieces of tread rubber torn off, etc.

Further information

Michelin has developed a specific training module on tyre regrooving. Your usual Michelin representative would be happy to present it to you.