Geek Speak

Semi-slick tyres have come a long, long way

Motor (Australia) - - CONTENTS -

Tyre tech could make your ‘track’ rub­ber re­dun­dant

THERE’S a clue in the name as to the rea­son why, up un­til about a decade ago, semi-slicks were con­sid­ered an af­ford­able, high­grip track-day op­tion, rather than gen­uinely road-friendly rub­ber.

‘Slick’, as in ‘oil’, de­scribes the lack of grip a tyre with­out grooved tread has in the wet. That’s why cir­cuitrac­ing cat­e­gories such as tour­ing cars and F1 have in­ter­me­di­ate and wet tyres to choose from.

Semi-slicks have al­ways been semi-slip­pery in the wet. The limit for day-to-day drive­abil­ity, up un­til rel­a­tively re­cently, was a set of grooved, yet sticky ul­tra-high per­for­mance (UHP) or S-com­pound tyres. This is be­cause when you’re driv­ing your hot car on the road and it rains, you can’t ex­actly dash into the pits for a set of wets.

As well as hav­ing less grooves lead­ing to an in­creased road foot­print and more grip (in the dry), semi-slicks use an even stick­ier ‘R-com­pound’ to fur­ther in­crease grip. How­ever, this op­tion in­tro­duces yet an­other com­pro­mise.

Softer rub­ber re­sults in more rapid wear, even when you’re not ex­ploit­ing the ex­tra grip. In com­bi­na­tion with strong side­wall and car­cass con­struc­tion de­signed to stand up to the rigours of rac­ing, and an ag­gres­sive tread pat­tern, you have a tyre that’s nois­ier and bumpier than true road rub­ber.

It was good ad­vice, then, to keep your semis on a sec­ond set of wheels for the track – the Toy­ota 86 boot was fa­mously de­signed to swal­low four track-day wheels and tyres (with the back seat flat­tened).

If you ran semis on your road-car and gained a mean­ing­ful ben­e­fit over UHP tyres, you were clearly com­fort­able with los­ing your li­cence. These are tyres that don’t grip to their full po­ten­tial un­til they’re up to op­ti­mal op­er­at­ing tem­per­a­ture – a tem­per­a­ture nor­mally only found when on a race­track.

If the semis on your daily Honda In­te­gra Type R didn’t pro­vide any ac­tual ben­e­fit – just lots of draw­backs – you were a track-star poser; and you knew it.

How­ever, like many other high-per­for­mance tech­nolo­gies, motorsport is to thank for progress when it comes to semi-slicks.

Hankook is an ex­am­ple. Once upon a time a no-name brand you wouldn't dare con­sider com­pared to the Euro­pean tyre man­u­fac­tur­ers, Hankook owes its in­volve­ment in DTM and Euro­pean For­mula 3 for the de­vel­op­ment of its road-friendly semi-slick, the Ven­tus RS-3.

When you're driv­ing your road car and it rains, you can't dash into the pits

Like many semi-slicks these days they've come leaps and bounds for wet weather per­for­mance in par­tic­u­lar.

Just ask the Aus­tralian Pro­duc­tion Cars race se­ries where the RS-3 is the con­trol tyre. There aren’t any wets or in­ter­me­di­ates.

Yep, the ol' semis have come a long, long way in­deed.

An in­crease in the per­for­mance of road cars has forced track­honed com­pounds and fea­tures to fil­ter down the ranks

Newspapers in English

Newspapers from Australia

© PressReader. All rights reserved.