New Zealand Historic Saloon Cars Under HRC

[Kiwiboss]

Thanks Jac, this here is the earliest photo I have managed to find of a car on what appears to be slick tyres. This is from 1973, which coincides with what you said about Moffats GTHO. However, I can't say with 100% certainty if these really are slicks, or just treaded tyres that have worn down?

Pretty much from about 73/4 onwards(as per JR's Sidchrome Mustang) when Saloons started raced under Schedule E(basically IMSA or Sports Sedans) they went to the wide 14inch rims mostly from F5000 cars hence used whatever tyres the F5000's raced on, im pretty sure they were still treaded? and certainly no radial slicks! also I can remember my Dad sending away worn out wide tires and getting them re-treaded as a slick, the speedway guys done the same except they grooved them, from memory as a kid new wide race tyres were considerably expensive and hard to come by in the day(true Jacmac?).

[Steve Holmes]

Pretty much from about 73/4 onwards(as per JR's Sidchrome Mustang) when Saloons started raced under Schedule E(basically IMSA or Sports Sedans) they went to the wide 14inch rims mostly from F5000 cars hence used whatever tyres the F5000's raced on, im pretty sure they were still treaded? and certainly no radial slicks! also I can remember my Dad sending away worn out wide tires and getting them re-treaded as a slick, the speedway guys done the same except they grooved them, from memory as a kid new wide race tyres were considerably expensive and hard to come by in the day(true Jacmac?).

Yep, thats pretty much it Dale. In fact, Formula 5000 cars were running on treaded bias-ply tyres until the early 1970s, its really all there was, and Formula 1 cars would have been the same. When tyre technology proved that a tyre with no tread provided better grip than one WITH tread, all racing tyres pretty much fell into line, be they for single seaters or sedans. It was really just because of the tyre wars taking place, that manufacturers were constantly looking to improve grip.

Here is Graham McRae's McLaren F5000 on Goodyear Bluestreak tyres, the same as the HMC cars, Historic Trans-Am in the US, etc run now!

[Jac Mac]

When I first built the MKII Cortina OSCA car I used rear ( slick ) 15 x 12.5 w from George Beggs F5000 cars ` $30-$50 ea IIRC and some much older 15x 10 intermediates ( Dunlop) from one of the older cars on the front. Was just reading an old tire article that mentioned slicks making inroads to circuit motorsport from 1969 onwards.... gotta remember that saloons took a while for everyone to realise that a wider tire needed a geometry rethink to keep the tread square to the surface for any older stuff. Tires were harder to get, Graeme Lawrence had the Goodyear franchise tied up. Expensive, yes, had to order in advance etc until the import thing freed up.
The slick retreads were crap, tried some at Coronet Peak Hillclimb once, black marks everywhere but bugger all acceleration. Put the GN Begg budget specials back on and went much faster. Biggest worry was finding loose gravel from previous rally guys who have no respect for road width!

Extra, Slick tires were first used by Nascar @ Talledaga in 1969.