Bald tyres on track

[Jon]

On another thread I said this:


I have since bought two GSD3 F1s, and those are now in the shed, nice and evenly bald having done 15000miles or so, and no blow outs on those. Sat ready for the front of the car next track day :)


and had these replies:


I really don't understand the rational of using bald tyres on track. You're going to be pushing your car for a longer period of time, so you use tyres which are illegal and dangerous for use of the road. Yeah use spare shit wheels, but bald tyres :wack:



Jesus,

Bald 15,000mile old tyres on the front for trackdays,

hope to feck Im not near you when you get the physics lesson about how tyres are made - once through the proper tread you will find the carcass rubber that they bond the tread to which is what bonds to the steel or canvas belt below. This is usually VERY soft and wont take heat from trackdays too well.

If you want the best performance from raod tyres for track use you want about 1-2mm of tread, this stiffens the movement of the treadblocks so you dont get as much slip or treadwalk, but it also means you are running on the compund designed to take the heat, stress and friction of the tarmac, without running the risk of eating into the carcass underneath.

I can give you Yokohama's technical department phone number if you like !!
:D :D
J.

Just started me thinking.
I've always saved tyres too bald for road use, for track use.

Am I wrong ?

[Moby-Dick]

given that you are going to be pushing tyres on track harder on the roads , and if you have an off , its going to be at higher speeds than on the roads , it would seem like a very false economy

[danny-mac]

Am I wrong ?

I would say not, but if it rains:eek:

[frisbee]

1-2mm is what I would class as bald. Illegal or close to illegal on the road, fine for the track. Brand new roadtyres would just overheat and fall apart.

[sparkyhx]

test years ago on some car programme proved that legal limit tyres stopped quicker and gave better grip than new tyres with full tread. ........in the dry

It was as expected totally different in the wet.

I would also say that the lack of tread would also help them not to heat up as much and risk delaminating.

As I said, dry and wet its a completely different ball game.

Legal limits on tyres are a compromise between grip in the dry and grip in the wet

dunno if bladerider is right or not. I can't see the compound of the treat varying over the depth of the tread, certainly don't use completely bald tyres but I would have thought 'legal limit' ones would be fine.

[SM]

"Bald"

I always used tyres that were past legal, but still had tread for trackdays. I worked on the theory that the legal limit is there for wet conditions, and in the dry you could have use of the last 1.6mm of rubber.

I often went to the wire, and at that time I never noticed a real differance. I think I would now, as I push much harder these days ;)

[CNHSS1]

its common for race classes thatn have to run on road tyres to shave the brand new tyres tread off to min legal limit.
in the dry...
a tread block moves around if its 6mm thick and very quickly overheats, ruining the grip. a 1-2mm tread block doesnt suffer the movement and bending loads so doesnt overheat and gives more grip. the more sensible temperature change also stops the tyre pressures changing as much.
that said tyres that have had a hard life and have ben cooked (drifting, excessive wheelspin/heat cycles, will have the rubber compound hardened so not as good as a fresh 'shaved' tyre.
in the wet...
lethal:wack:

some tyre manufacturers do alter the rubber compound through the tread depth, bridgestone S02s were a popular example. starts of harder to resist tread block movement and then got softer as they wore down

[SM]

some tyre manufacturers do alter the rubber compound through the tread depth, bridgestone S02s were a popular example. starts of harder to resist tread block movement and then got softer as they wore down
Thats probably why I thought they were crap when I got them, but once they were old were actually very good.

[kam]

I have that when drifting, new, expensive tyres that are very good for grip just fall apart when i drift on then. When the tread is about 3mm they last ages and grip well.

I'd say that theory is correct :thumbs:

[razza987]

I've always saved tyres too bald for road use, for track use.

Am I wrong ?

Define your use of the word "bald".
To me bald means completely worn, no tread.

[Jon]

I didn't specify, so as to get a general opinion.

For me personally, I hoard wheels/tyres that aren't fit for the road. Either evenly worn down to the wear markers (about 2mm), or as my car wears the inside edges of its front tyres on the road, I have a few which are badly worn on the inside edges, while having several mm of tread elsewhere.
I'm on standard suspension, so trackdays scrub off the outside edges of the remaining tread.

[razza987]

I'd use tyres that are below the legal limit, but I wouldn't use tyres that were "bald". That part of the tyre isn't designed for grip.
IMO what you're doing is fine :)
Raz

[bladerider]

I have said what I think is right and wrong on this topic,

In fairness to Jon he said his tyres were "Bald" which last time I checked my Duncan Goodhew dictionary meant similar to a rent boys ahse !!!

Worn to the legal limit means precisely that, or even illegal, it most certainly doesnt mean bald, hence why I gave the somewhat severe reply that I did.

Do a google search and learn about tyre construction techniques if you wish, or get and old tyre and a sharp knife and have a look and you should just about be able to see the different compounds of rubber that are used even in standard road tyres. Silica content and a host of other variables make up how this rubber wears down and hence when the tyres are genuinely bald and therefore much closer to the core makeup of the tyre unusual things can happen and certainly when Im ontrack I dont pootle around in the same way as on road, and hence dont want my tyres to suddenly be the reason im having a closer inspection of the armco than I had planned on !!

Save money by all means

Use tyres with 1-2mm of tread on for the reasons I had already mentioned which others have echoed on this thread
By all means use baldies but be aware that you are asking for trouble
Or, dont attend one trackday, save the fuel money as well as the entrance fee, dont buy that latest worthless sticker/valvecap set/stick on carbon tat/big gay wing and spend all that cash on a set of Ao48's and get more out of you and your car for 3 or 4 trackdays instead and realise what the true priorities are !!

Happy tracking !!

:D :D :D

J.

[schumi84]

I am all in favour of saving money/getting every last bit of use out of something, so if it isnt going to be putting you or anyone else in danger by using them, then go for it.