Radial Wets / Crossply Slicks

[James Williams]

I can vouch for Yobdabs used wets. Excellect value and service and they even qualifyed for a run off at a wet Shelsley!

[Andy]

There seems to be 2 schools of thought on wets :-

1. You run a hardish compound to make the tread stand up, penetrate the surface water and contact the tarmac.

2. Run a soft compound which will give the best grip whatever the surface is.

I run a lightweight bike engined car like you, and have found the second option best. Our cars don't compress the tread enough to worry about it not standing up.
Also remember that in the wet they run cold, and no matter how hard you drive them they don't warm up. (damp is different).
As for wear, they die of old age before major organs wear out.
Do you run the same width tyres for both wet and dry conditions?

[Radical]

Running proper wets in anything other that full wet (monsoon) conditions ruins the edge of the blocks very quickly. One double entered event at Kames in actual monsoon conditions was still enough to round all the edges on the blocks.

When you buy the new ones you will need to be carefull not to get caught running them in anything other than full wet. Having peviously only ever having old hard and useless wets it caught me out, the massive grip in the wet was however extremely surprising.

However, I found though that in the damp they not only suffer damage but offer much less grip than the slicks. Probably due to the blocks moving around.

[Craig Powers]

Originally Posted by Andy

Do you run the same width tyres for both wet and dry conditions?

Currently, yes.

13 x 7.2 / 20 on 8" rim
13 x 9.0 / 21 on 10" rim

(I recall)

[Craig Powers]

Originally Posted by Radical

Running proper wets in anything other that full wet (monsoon) conditions ruins the edge of the blocks very quickly. One double entered event at Kames in actual monsoon conditions was still enough to round all the edges on the blocks.

When you buy the new ones you will need to be carefull not to get caught running them in anything other than full wet. Having peviously only ever having old hard and useless wets it caught me out, the massive grip in the wet was however extremely surprising.

However, I found though that in the damp they not only suffer damage but offer much less grip than the slicks. Probably due to the blocks moving around.

Yes totally agreed but changeable weather is just one of the crosses we have to bear. If you are stuck in the start queue and the weather changes there isn't much you can do. (other then decline the run and cause startline havoc).

The other option is have a intermediate tread pattern, with the the grooves not cut to the outside edge of the tyre. I have done this on an earlier car (911) but too long ago to remember and in any case ithe comparions are pointless.

[morrich]

Craig
I am running an OMS 2000M with a GSXR 1000 with A91 crossply slicks and
A15 radial wets. I found the performance of the radial wets far better than the previous crossply wets (age of the rubber etc would have contributed) but the differential was huge and so much that I decided to leave the crossply set up in place when changing to the radial wets.

[whimsy]

On tyre size - I run the same sizes wet or dry. I did, many years ago, run FF2000 size wets but F3 sized slicks for the dry, but I can honestly say that when I eventually increased rim and wet tyre size (as more funds became available) so I had a lot more confidence in the wets. Then again that was in the pre-Avon era of M+H; so perhaps it doesn't translate to today!

The edges of the blocks on wets are going to suffer sooner or later. The worst conditions are when the track is drying fast, except under the trees (eg Esses at Prescott or Shelsley). Slicks are right for most of the track, but lethal unless you are really careful under the trees. Under these conditions my approach is to leave the wets on, stuff the block degradation, and bank on a better chance of keeping the car on the track, making the finish, and avoiding very large bills and possible injury. Not everyone will agree, and with great reactions and a very measured approach I'm sure slicks are marginally better. If in doubt - use the wets - is my motto! And live to fight another day!

Once the blocks show a little edge damage, the tyres aren't written off. Prolonged use and major damage will render them pretty useless, but most wets I've had show signs of edge damage pretty quickly but still work well.

Now if only we could guarantee consistent track conditions all the way up the hill............

I think the conditions that frustrate me the most are where its teaming down - so you fit wets. One car goes off, followed by another, and by the time they've been recovered, you're sitting in the car, the sun's come out, the track is steaming, and there are maybe 6 cars to go before you. You just know if you get out and change to slicks (a) it will rain again and/or (b) you get back in the car sweating like a little piglet and fail to drive well because you're too wound up and (in my case) you're glasses steam up!!!!!!!

Aaah - the challenge of hillclimbing!!

Andy

[Craig Powers]

Originally Posted by whimsy

....Under these conditions my approach is to leave the wets on, stuff the block degradation, and bank on a better chance of keeping the car on the track, making the finish, and avoiding very large bills and possible injury.

I totally agree; I do the same. If it is raining or very wet I just tip-toe round. Wets are a psychological help.

It isn't that often that the rain persists all day (*). The final results and fastest times are seldom set on wets. Usually the conditions allow a run on slick at some point.

* except at Harewood

[johnbull]

Don't know how much of this helps, seeing that we are racing 2000 miles away from UK and under very different conditions, both climatic and otherwise.

We run a modified ex Formula BMW rolling chassis with a Kawasaki 1400 engine, in both short hill climbs (Malta), long hill climbs (Italy) and circuit racing (also Italy). Tyres have always been Dunlop radial slicks - 8 inch front and 10 inch rear.

As far as wet tyres are concerned, we do have a set of Dunlops, but have never had occasion to use them. This is not meant to be a facecious statement, but a statement of fact since here in Malta hill climbs are simply postponed by a week on the rare occasions when it rains, and in Italy we have never yet hit a wet Sunday. In other words I can't be of much help with wets.

As far as the dry is concerned, softest slicks possible on the short hills, and fairly hard ones on the circuits. That's pretty obvious. Cambers are also different on the different applicatons, with a maximum of 2 degrees front and 1.5 rear for the hills, and 3.5 and 3 for the circuits.

The radial tyre is much more "compliant". It's tread area remains flat whereas the sidewalls flex, giving a better and more predictable ride. The car is actually supposed to be easier to drive on radial slicks.

If we look at F1 we see that almost all the cars springing and damping is done by the high sidewalls of the radial tyres. I think that should be enough to convince us.

We are presently in the throws of changing class (supercharging he 1400) to run in the 2000 class, and this means going up a couple of inches in rim and tyre widths too. Fortunately Dunlop have just recently started producing their HC100 compound tyre expressly for hill climbs, and we already have a couple of sets of these which we have just started using, with very encouraging results.

[Craig Powers]

Originally Posted by James Williams

I have been told you can't cut Radial slicks into wets, but don't understand why? I haven't done it based on this advice. If anyone has any experience of cutting radial slicks into wets, I would be interested to know!

I haven't mixed Crossplies with Radials, I have always thought it best to be on one or the other on both slicks and wets. Sorry Craig, I haven't really helped you there, but a good thread where we might all learn a little.

Feedback to this earlier tread...

I am very pleased that I went with BMTR's suggestion of using Avon crossply slcks and Avon radial wets.

The wets were essential wear at Elvington this weekend and they gave excellent grip levels in very challenging condtions. It was very difficult to get the car off the line, but once rolling the car felt good, the tyres cleared the standing water very well and grip levels were quite remarkable for the conditions.

The compunds are A15. The fronts are moulded and the rears are hand cut from slicks (which covers James' query, above)

I am using typical crossply suspension set-up i.e. little or no static camber and I left the new Anti-Roll bars at their dry setting. There seemed no reason to change the bars; the car was fairly neutral, but with mild oversteer in places.

Craig Powers
OMS2000m ZZR1100