CAP THAT!
Page 24
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by CM reporter
UP TO DOUBLE normal tyre life without loss of roadholding performance is claimed for Kenprest, a new tyre recapping process developed by Retreading Equipment Ltd, Mill Lane, Alton, Hampshire 0U34 2QB.
Producticn of recapped tyres will start in the Spring of 1975; prices have yet to be announced. Initially, only long-distance haulage tread patterns will be available.
Over 100 recapped prototype tyres are being tested in the field and during a visit to the company I saw some that had been recalled for wear measurement. One tyre had been fitted to the leading offside wheel of a widespread tandem-axle semi-trailer operating at 32 tons gcw. It had covered 96,540 km ( 60,000 miles) and had sufficient tread depth remaining to permit an estimated further 53,097 km (33,000 miles) of service.
I was told that the similarly capped twin tyre on the same wheel gave a projected service life of nearly 131,938 km (82,000 miles).
Another Kenprest recapped tyre had been fitted to the rear-steer axle of an eight-wheeled 30-tormer. The axle track was 8mm (0.3 in) out of alignment, but the recapped tyre covered 64,360 km (40,000 miles) whereas, I was told, a new tyre would last only for about 32,180 km (20,000 miles) under similar conditions.
Unlike the existing Kentredder system, the cap tread is cut and vulcanized before bonding to the tyre carcase.
The tread band is about 5 per cent longer than the carcase circumference and it is compressed onto and bonded to the carcass.
The cap remains compressed throughout its service life and any splits inflicted on the tread tend to close up. The prototype tread band has a transverse splice and the compressive forces eliminate any tendency for it to open. The final production tread band will not have a splice.