Wet track day - road rubber or track day tyres?

[itiejim]

I'm off to Mallory Park on Saturday for the first run in my Alfa 75 track car. I've done plenty of track days over the last few years, mostly in Elises, but have always run intermediate tyres like Advan Neovas or AD08s (without a second set of rims), however, this car came with a set of virtually new RE720s as road tyres plus a set of Dunlop DZ03 on rims for track use.

The weather forecast for Saturday is for rain and I just wondered what the PH collective thoughts on the suitability of both were given the conditions?

[Nigel_O]

I've found that trackday tyres are fine in the wet, until there's any standing water. At this point, they become a liability.

At a recent Ten of the Best, I could happily hit 150mph on wet tarmac, but on the way home, as the rain worsened, I was struggling for grip at much above 50mph

Take both sets of wheels and swap to the road tyres when you start to lose traction, or aquaplane

[HustleRussell]

Trackday tyres unless there is a lot of standing water on the line or on the straights. Whichever tyre you go for, remember to go up in pressure.

[thunderbelmont]

That's an interesting comment - going up in pressure.

When I raced on road tyres (Toyo's), I used shaved tyres to 4mm treat for wets, 2mm for drys. If it rained, we reduced the pressure by 6psi all round, for two reasons.

1. the tyre heats up quicker with the lower pressure
2. Lower pressure effectively reduces the "spring rate" of the tyres, making it softer.

This particularly useful as our suspension had to be fairly standard, and changing springs wasn't simple(no adjustable platforms to correct ride-heights, etc..)

For example, I ran Toyo Proxes T1's (195/50/15) on a small FWD car weighing 780Kg, and ran 42PSI front 36PSI rear in the try, and 36PSI front and 30PSI rear in the wet.

As for the tyres to use, then take both sets. If the track is just damp, then trackday rubber, if wet (I mean raining, and standing water), road tyres.

[itiejim]

Thanks folks, interesting commentary on the pressures. I'll take both sets along and see how I get on.

[HustleRussell]

thunderbelmont- this does seem to vary wildly depending on the vehicle and tyre type. I agree that the extra compliance gives the impression of more progressive characteristics and that the sidewall flex helps generate heat. However, I use a road-orientated tyre and going up in pressure reduces the tyre's contact area which increases the force per unit area at the tyre's contact patch. This, on my car at least, is more helpful to generating tyre heat than the movement of the carcass. On the other hand, I do have 8mm tall tread blocks shuffling around under there which no doubt helps!
I can see how lowering the pressures of the rear tyres of an FWD race car would help because there is little else to heat them.

[refoman2]

personally im an increase the pressures on road tyres in the wet kind of person.surely having the tread pattern doing what its designed to be done,ie removing water,works far better when the tyre is harder and tread pattern more pronounced????????

[weed]

The track day spec tyres need to be in the tyre manufacturers optimum recommended temperature range in order to generate grip, so a lower starting pressure cold will make them generate more heat and allow the tyre to generate grip earlier.
Having said that, if the ambient temp on the day keeps them from getting into their optimum temp range then it's going to be a slippy day.

I have always found track day spec tyres to be as good if not better than the best ultra performance street tyre on a wet surface as long as you don't encounter standing water.


m

[weed]

The track day spec tyres need to be in the tyre manufacturers optimum recommended temperature range in order to generate grip, so a lower starting pressure cold will make them generate more heat and allow the tyre to generate grip earlier.
Having said that, if the ambient temp on the day keeps them from getting into their optimum temp range then it's going to be a slippy day.

I have always found track day spec tyres to be as good if not better than the best ultra performance street tyre on a wet surface as long as you don't encounter standing water.


m

[weed]

The track day spec tyres need to be in the tyre manufacturers optimum recommended temperature range in order to generate grip, so a lower starting pressure cold will make them generate more heat and allow the tyre to generate grip earlier.
Having said that, if the ambient temp on the day keeps them from getting into their optimum temp range then it's going to be a slippy day.

I have always found track day spec tyres to be as good if not better than the best ultra performance street tyre on a wet surface as long as you don't encounter standing water.


m