When filled with mud or snow, air­less tyres be­come like Fred Flin­stone’s char­iot

4 x 4 Australia - - Gear -

MICHE­LIN’S air­less tyre, the Tweel con­cept, lobbed 11 years ago and was a mod­ern in­ter­pre­ta­tion of the old buggy wheel. Ex­cept this time, the ‘spokes’ were a lat­tice-like in­ter­wo­ven struc­ture that ab­sorbed road shocks like a pneu­matic tyre. Miche­lin has gone quiet on the Tweel, but Bridge­stone showed some­thing sim­i­lar with its air­less tyre, the Air Free Con­cept, at the 2013 Tokyo Mo­tor Show.

The Air Free Con­cept tyre has a spoke struc­ture made from re­us­able ther­mo­plas­tic resin that stretches along the in­ner sides of the tyres to sup­port the ve­hi­cle’s weight. Along with the rub­ber tread, the materials used in the tyres are all re­cy­clable.

Both the Miche­lin and Bridge­stone tyres have a prob­lem with the lat­tice-like ab­sorbent part of the tyre: when filled with mud (es­pe­cially when dried) or snow, they be­come like Fred Flint­stone’s char­iot wheels – there is no give in the tyre. The other prob­lem is that, in Bridge­stone’s case, the tyres only sup­port a ve­hi­cle weigh­ing 410kg and have a max­i­mum 60km/h speed. The air­less tyre has a way to go yet be­fore it’s a pro­duc­tion real­ity.

The clos­est thing to a punc­ture-free (air-filled) tyre is Con­ti­nen­tal’s Con­tiseal tyre, which has a sticky, vis­cous layer from shoul­der to shoul­der along the in­ner car­cass. It’s not de­signed or in­tended to act as a per­ma­nent punc­ture re­pair; it’s more like an au­to­matic plug re­pair kit.

If an ob­ject up to 5mm in di­am­e­ter pen­e­trates the tread, the Con­tiseal layer en­velopes the punc­tur­ing ob­ject and gives a near in­stan­ta­neous seal. If the punc­tur­ing ob­ject be­comes dis­lodged from the tyre, the ma­te­rial is de­signed to seal most holes up to 5mm in di­am­e­ter. Con­ti­nen­tal claims there is no tyre per­for­mance detri­ment, but it’s cur­rently not of­fered in its 4WD tyre range.

Miche­lin’s Tweel con­cept tyre has a ways to go yet!

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