hillclimb tyre pressure advice

[sambb]

After some advice on starting/cold pressures for:
1: advan AD08R standard size and
2: bridgestone RE003,

This is for hillclimbing where there is zero opportunity to get heat into the tyres and the total run goes for 1min. ie I need stone cold grip by the first (20metres away) corner.
I know that on the track you might set the yoko's somewhere around 30psi and the street tyres around 35psi but I'm pretty sure that won't hold true when I can't get a pressure change into them. Even if each was set optimally for what I'm doing, I'm actually wondering if the RE003's might go better than the yoko's in terms of giving instant cold grip
thoughts!

[Stuwey]

My daily Polo is (or at least was) on RE002s. My mini is on A048Rs. Without doubt, after corner 1, the Yoko's have more grip, damp or dry.

My Polo went up the Collingrove Hillclimb on the RE002s, and it was definitely quicker once I dropped the pressures down to around 32 (front) cold. It was a chilly cold winters day though, with no track temperature at whatsoever.

Never competed in the mini on bitumen, so can't comment definitively but i'd be surprised if a road tyre would outperform an R-Spec ADVAN.

Run the Yokies, maybe 32psi?

[brad]

I'd run low - maybe as low as 28psi.

I was driving a Corolla yesterday at 24psi & couldn't believe how much grip it had. Felt like I was driving a pudding & response wasn't terrific but you could hook it around corners.

[seangti]

Both tyres are for street, Yoko having a track oriented intent though still not a semi. Probably ideal for hill climb though. As such, perhaps start around the 30psi, check at the end of the run to see what it's doing. I'd be surprised if it's gained 2psi. I can't see you doing much about that on cold tyres and within a minute.

Would be looking at suspension geometry, taking note of pressure variation front to rear. May also be worth getting a tyre temp sensor (pyrometer) to see what heat is being spread across the tyre and fiddle with geometry and pressures accordingly. A good GPS laptimer may help too, understanding max g'force achieved.

Also bear in mind an old tyre takes longer to heat. My old semi's are useless in the first session (5 laps) and improve thereafter.

Please share your experiences, keen to see.

[sambb]

So just to confirm are you guys saying that the pressures should be pretty similar 30psi (+/- 2psi) even though the tyres are fundamentally different? Brad when you said to even go as low as 28psi, was that for the bridgestones?
The weather report is saying max 16 degrees so it'll be a cold morning and 40% chance of rain. If its just patchy damp yeah the yokos would be fine but if it turns out to be properly wet I'm worried the yokos might be a bit skitish - I'm virtually on the indicators. The **** of it is, I have to make a decision now on which tyres i'll run on the front as I don't have a spare pair of front rims so have to take the punt and commit. Might have to play it safe in case it rains and put the bridgestones on and give myself enough time to scrub them in before saturday practice. grrrr decisions!

[seangti]

Will you be doing hill climbs often? If so, pick a tyre you'll be running in the future and make incremental adjustments on pressure. Wouldn't; worry too much about one tyre or the other initially. Higher tyre pressure will make it more progressive when it slides, but sacrifice grip. First you need a benchmark to make adjustments from.

If you run the Bridgestone, start with higher than 30psi, would be more like 34-36psi as you don't want to rip a tyre off the rim.

[brad]

I meant for either.

It's just a club level hill climb isn't it? You're meant to make mistakes & adjust as you go along.

seangti - you won't rip a tyre off a safety rim at 28psi - not at the speeds the OP will be doing on a "first outing" hillclimb (unless he's really good). I used to run as low as 26R / 20F in the dak-dak.

[sambb]

The hilclimbs are run just about once a month until october when it goes a bit more quiet over the break. This will be my first hillclimb. I'm not getting ahead of myself obsessing about times in all this, I'd just have preferred to have been going there with tyres I'd been on for a while and understand. To have to switch to bridgestones and slimey new ones at that due to the threat of rain is a bit of a bugger.
In the future, once I get another rim i'll be able to have the yoko's for dry events. I've spoken to a few people about street style 'semis' and got the feeling that federal RSR's grip almost instantly and that the AD08R's are nearly as good in that department but a little better when its patchy damp so I'd go with either of those. The bridgestones will be the daily/wet event tyres.
The event I want to feel sorted by is the last King Edward Park hillclimb that may ever run which is in October - this weekend though will just be finding my feet.

[kaanage]

My question is why AD08R? Yes, they are VERY grippy and from all accounts, you could run them as a daily tyre but if you get another set of rims that let you easily switch, then I'd get a set of full semis as they are quicker. I posted up a video last year of the PoD vs a Clio last year where the Clio was miles more powerful but the PoD made up the difference through the turns - the Clio was on AD08Rs and the PoD was on A048Rs. The AD08Rs would probably be a bit better in the wet but then I'd run the RE03s (what I intend to get as my "wet" track tyres once I wear out the Conti Premium 2s).

On a hillclimb, you won't have enough distance to get tyres properly warm so I'd be starting around 32psi to make sure steering was responsive from the start. And I agree with Stuwey that the track tyres will outgrip the road tyres in any conditions that aren't properly wet. I broke in a set of A048Rs in the hills on a cool morning and scared the $hit out of myself with the corner speed that the PoD was holding without it ever feeling like it was near the limits. When I reached the end of the 18km of twisties, I pulled over and found the tyres barely warm to touch (plus that I had a sore neck)

But since you're starting out, the RE03s will be a lot more progressive on breakaway so I'd hold off the AD08Rs until you get the extra rims.

[sambb]

righto. I always thought that proper semis needed to be brought up to temperature before they'd properly grip. Thats why I'd only really looked into 'street semis' like 595's, AD08R and hankook RS-3 thinking that they'd get there quicker. Yeah I mean if you think a proper semi would grip from the get go (I can't even do an effective burn out with my open diff axle tramper) i'll definitely look into that because the plan is to just use street tyres in the wet and swap on a pair of semi fronts when its dry.
I've been running the AD08R's on the front as dailys after my dunlop sport maxx R/T's evaporated after only 15,000km. yeah i've definitely found that the AD08R limit is higher in damp conditions than the dunlops provided you are carrying some speed and can lean on them a bit. In really slow speed corners though I've found them to be a bit treacherous as it gets wetter. But they let go very suddenly in the wet and don't tell you they are about to in the way that the street tyres had thats for sure. Its just a question of keep them on and hope it doesn't rain or get the RE003's on and hope it will!
The AD08R's are nearly out of legal tread so i'll probably save them for a few more events and then i'll look into the dedicated semi's like you said.
If I do get the RE003's put on whats the quickest way to scrub off the greasy new top layer. Will a quick flog on a favourite stretch have them ready?