Tyres....again

[skydragon]

All being well, I'm planning to do some Hillclimbs next year in my 1.6 K-series Caterham (currently Supergrad spec).

 

I guess I'm looking to enter in Class 4 of my local (Harewood) BARC hillclimbs, as per;

 

Class 4 Road Modified Kit, Replica, up to 1700cc

non ferrous.chassis construction cars and Spaceframed

Cars, excluding non car derived engines.

 

presuming my choice of class is correct (??), looking at the Harewood Class 4 rules for 2008 I note

 

Wheels are free but

the only permitted tyres within these classes

are those defined in the 2007 or 2008 MSA

Technical Regulations, List 1 A

 

At the moment I'm (fairly happily) using AO48r tyres which are list 1B and therefore wouldn't be allowed in class 4.

 

Does anyone know which is the best list 1A tyre for hillclimb use on a Caterham ?

 

I'm running 13" wheels, so that will possibly limit my choice.

 

Yokohama A539's have been suggested as one possibity (??).

 

1.6 K Series EU3, 2003, ex-SuperGrad car. Ali/Red.

[Richard Price]

skydragon,

Most of the quickest cars running list 1A tyres are running 15" wheels with Stunner Scudo tyres.

There have been a few running Yoko A539's and they don't look to be too far off the pace.

I'd guess, that to be at the sharp end of that class, you'd need another 60-70bhp as well as slightly better tyres.

Why not do some rounds of our own championship, where your car could be bang on the pace in our class 1?

[KenEvans]

Skydragon - I'm the bloke who suggested you post here instead of Pistonheads.

 

Are Stunners still eligible for 2009 Richard? I don't know I'm just asking.

 

Irrespective of the tyre, you would benefit from going to 15 inch wheels, the shape of the contact patch gives better traction which is vital on list 1A tyres. You can usually find second hand ones on Blatchat.

[skydragon]

Thanks for your advice chaps.

 

I'd hoped to stay with the two sets of 13" wheels I already have... but I guess I could buy a 15" set next year.

 

I'd guess, that to be at the sharp end of that class, you'd need another 60-70bhp as well as slightly better tyres

 

Money allowing I'll be getting the engine tuned (DVA?) over the next year or so, to around 160bhp. The other key upgrade I want to add is a LSD.

 

Why not do some rounds of our own championship, where your car could be bang on the pace in our class 1?

 

I may well take part in some of the club events and would no doubt enjoy it. I live only 35 miles from Harewood, so that was one of my main motives for wanting to compete there. Next year's activities will depend a lot on what happens with work and money , so I'm probably going to be taking a cautious start anyway and although I've got all kinds of plans for car upgrades and events, a gentle introduction next year wouldn't be a bad thing anyway.

 

 

 

1.6 K Series EU3, 2003, ex-SuperGrad car. Ali/Red.

[skydragon]

Irrespective of the tyre, you would benefit from going to 15 inch wheels, the shape of the contact patch gives better traction

 

Thinking about this topic some more. If this is true, why do many people use 13" wheels for Seven racing ?

 

I thought 13" wheels gave better acceleration as opposed to larger wheels (good for sprint/hillclimb).

 

Keen to understand more.

 

1.6 K Series EU3, 2003, ex-SuperGrad car. Ali/Red.

[Richard Price]

skydragon,

There are several theoretical advantages and dissadvantages of each wheel and tyre combination.

13" wheels tend to be lighter than 15" wheels, but the choice of 13" list 1a tyres is limiting. Conversely, choice of list 1B tyres is limited in 15".

 

All the quickest sprint and hillclimb cars that run list 1a tyres are using 15" wheels.

 

I run 195/45-15 tyres. These are roughly the dame diameter as 185/60-13 tyres so give the same effective gearing. I think there may be a slight advantage with traction is 195/50-15 tyres were used, but I choose to run the same tyres front and back, and with the 45 series tyres I can run a lower ride height whilst still having a little suspension bump travel.