333pg333

So I've done a bit of reading in here via search but just want to qualify some things. Assuming that most of us are amateurs and don't have a transport truck with 5 different wheels and tyre combos, what is the way to go between wets and intermediates? When I say inters, I mean a soft compound R spec as opposed to a full wet. We don't have quite the choice that you guys have in the US so I'm concerned with buying some wets and ruining them by running in anything but teaming rain. The nature of our events is generally 1 outlap followed by 3 hot laps then a cooldown lap. All against the clock even though you can pass or be passed on the track. I either use a full slick or R888 and neither are a realistic choice for even a damp surface. Generally they won't let us out on a track with pools of standing water but we do go out in the rain. Unusually for Sydney we have had a fair bit of rain this season. Seems to coincide with me taking my slicks out to the track!!
So I've decided to invest in some slicks. I have a spare set of 17" wheels which are 8.5" and 9". This is pretty narrow compared to the normal 10" / 285 all round I use with the slicks but I'm thinking that having narrower wets is not a bad thing.
My major concern is just how long can you stay out in anything but wet conditions? At this stage I'm looking at Dunlop R92 at 240/625 R17s. Narrower than my normal tyre so will this help in reducing aquaplaning?
http://tinyurl.com/qehfbh
These cost us about $550AU a corner so it's not something I want to ruin on my first outing.
Do they need to be heat cycled? The info I'm getting is no. I understand that you run about the same psi cold as you would run a street tyre. I'm looking at about 32psi on a modified 951 with approx 3100lbs with fuel.

Any advice is appreciated.

aj986s

Toyo RA1's, with a reasonable amount of tread have a good history of working in damp conditions. However, if lots of standing water exists, full wets have an advantage. I've used Hoosier Wets a couple of times, and am quite impressed. However, they must be kept wet, or else they'll overheat and start wearing too fast. If rain stops, and a dry line starts developing, the Hoosier Wets should stay away from it as much as possible; you'll need to venture into wet spots/puddles in order to keep them cool. The rubber compound (A6/autox compound versus R6 track) is made to heat up quickly. Driven on dry surface they'll heat up, start graining, get greasy, etc.

I occasionally bring my 944 Cup car to DE's, and usually run on RA1's to avoid wasting more costly Hoosiers. So I have a set of RA1 inters available at race events.

Also, when running in the wet, I usually up the tire pressures, in order to reduce the contact patch to reduce aqua/hydroplaning. The additional PSI can vary based upon actual conditions. If lots of rain, little heat can develop on track, so must start higher.

333pg333

Yes we were thinking of going with some RA1s but they're getting scarce out here now and I think the compounds are all at least mediums.
Thanks for the feedback. It all helps.

Larry Herman

I think that you have it a lot easier to decide on wets or drys with your 4 lap window, than with a 30 minute race. You shouldn't hurt the racing rains even on a damp track in that short a time. Driving over the dampness down the straights will help keep them cooler, but I see your biggest problem being pressure. On a wet track, they will only gain a couple of lbs pressure as they will not get hot (typically just warm). On a damp track you could see significant gain due to brake heat warming the wheels and tire heat due to lack of cooling. This will not ruin your tires immediately, but they will get greasy because the pressures will go way above optimum. So that is what I see as the critical factor in your decision to run the wets - damp track start with typically lower pressures and wet track go with cold pressure a few lbs below desired operating pressure.

333pg333

Ok Larry so on a damp track wets will expand as quickly as normal R spec or Slicks? I guess why wouldn't they? In fact R spec seem to come up higher than slicks.
Also do you guys use the same size tyres with your wets? I don't have the opportunity at this stage even if that is wise, but I'm consoling myself that narrower will be better in the wet / damp.

Larry Herman

FWIW I've run similar sized tires because that was what Hoosier made. I don't think that I would purposely size them narrower, because I think that would only be an advantage in a flooded track where the chance of hydroplaning was significant. On your standard wet track, I had no problems with the Hoosier wets.

And yes, on a damp/drying track the pressures will come up a lot, but not as much as with Rs on a dry track.

M758

I have 3 sets of wheels for my 944 spec car.


When I ran RA-1's I could get all ranges of tires from these tires.


Dry = work down RA-1's with 3/32 nd or less tread.
inter = 4/32 shaved RA-1 rather fresh. This gave enough grooves to evauate some water, but also worked on a dry track if a dry line formed
full wet = 8/32 full tread RA-1. These could work on dry track, but were not ideal. However in realy heavy rain you wanted the soft feel of the tire's tall tread blocks and deep tread depth.


The good news with RA-1's was that if it looked like raing I could stock up and then burn them off in in the dry later on.

333pg333

Unfortunately Larry I've only got a spare set of 17's that are 8.5" and 9" wide so I'm having to go down in width. In any case they'll be way better than what I've been using in the wet to date.
It's like being on an ice skating rink wearing rollerblades thus far. lol

That sounds like a good setup Joe but were you dealing in the same compounds for each application? I thought RA1s were available in varying compounds. What are you going to use now that they're dying out?
I saw a Kumho V70a that looks like it might work for this sort of application, coming in a few different compounds for choice.

Patrick

M758

Same compund for all tires. I am now using R888's. Full tread will be for for rain and worn for the dry. Athough full tread works fine in the dry too..

daigo

Patrick,
Do I understand this correctly? Are you looking for a set of "intermediates"? And you are only doing 4 laps in an outing?
If so you have two things to consider. Even in the dry, 3 hot laps will just get the tires up to temp. Add damp conditions and you compound your problem. A good solution for an intermediate in this circumstance would be to get a set of Hoosier A6s which have a softer compound than R6s allowing them to come up to temp much faster, a big plus in the wet. The you would have someone (your supplier) put an intermediate rain tread pattern on them. This is a common practice for teams running slicks.

Try here:
http://www.rogerkrausracing.net/files/34215312.pdf

333pg333

Joe, I have been using the R888s for some time. They were available in Australia at least 1 year before the US (which is unusual). I have found them to be wanting in the wet, but that's understandable due to the R spec tread pattern. Perhaps you should get the 'GGG' compound for your wets?

Lorenzo, well I'm not sure entirely what I want as it's new to me. The gamble is getting full wets like the Dunlops pictured above, but having to come in to the pits every time a dry line appears. I like your idea about the A6s though. In fact, I'm going to try the A6 for my dry tyre at some stage. There was information from a Hoosier tech that said provided the A6s are properly heat cycled, they can be used for circuit work although will go off quicker. For our events they should be ideal. I am thinking of using R6s as an intermediate vs the R888s due to the softer compound. What do you think?

daigo

I agree with the rep, they will come up to temp faster, but go off quicker as well. Having said that it would not happen in your time frame assuming the track is not 4 miles long. Many hillclimbers use this technique (A6) because there is little time for the tires to come up to temp and the session is not long enough to overheat them. Perfect.
As for the intermediates you'd still choose the A6 over the R6 because you want the compound to be as soft or softer than your dry setup. Just use an appropriate pattern without too much tread.
We did run the Dunlops when we were running a Touring Car Honda a few years back. It was an amazing tire for two reasons. It stuck like glue in a down pour with standing water. It stopped raining and started forming some dry lines in some areas. All the other competitors burned up their tires while ours looked great at the end. Not new mind you, but not bad. The other folks were chewed to heck. The Dunlop rep had told us that was one of the greatest qualities of that tire, that they were more resilient to drier conditions.

GeorgeNZ

Patrick - fwiw if you are going to run DOTs in 17" the Dunlop DZ03G's are what we run for Targa (always wet and dry) so may be worth considering. While not quite as fast as the Bridgestone RE55S in the dry the Dunlops are great in the wet - RE55's are just plain treacherous in the wet by comparison.

dmwhite

hoosier wets shaved/worn down to 4/32's (or lower) make great inters...

M758

I run a spec tire in my class and that is the R888 in GG compound. The GGG is not sold in the USA and I don't believe comes in my size.

Also for me using the same tire in the wet as the dry is a key to keeping costs don't. I don't need a dedicated rain tire for the 1 time it rains a year. However if it does rain I can use the spec tire and still be ok.