Measure to the wear markers, not the bottom of the rain grooves. There are all sorts of fancy tread depth gauges, however good results can be obtained using a simple set of vernier calipers (carefully.) Measure tread depths at 3 points across the tread width and at 4 points around the circumference of the tire. The tire never reaches a stable hot working temp during the run, so you aim to be slightly under inflated at the start, about perfect in the middle and slightly over inflated at the end of the run. Sometimes it is better to work from the tire wear. With the short runs, you can get quite a lot of variance in your data because individual driving errors have a greater effect on the overall result. *The UK MSA have two lists of tire brands and types, list A and B, which are broadly "genuine road tires" and "road legal track tires". He suggests B list* tires like the Toyo 888R are typically worth 4 sec per minute over good A list tires. We call your event "sprinting" I have a friend who is very successful at this type of event. ![]() PS : did look at : viewtopic.php?f=14&t=991. The story being that nitrogen is less susceptible to expansion ( read = increase in pressure) with increased temperature? We will see if this makes any difference.ĭoes putting not air but nitrogen gas into tires help. Practically we will be able to check tire temperature after the first run and see if the differences are significant - and adjust if necessary. ![]() This will also influence handling in curves. I expect the air tempt to be as much as 27deg.C and the track temp may be as much 37-40 deg C. So it seems that selecting the right tyre pressure to start off with and to warm up the tires before the run is what we will try to do. Note that the kind of racing we do, is limited to ca 1,5 - 2,5 minutes runs with many curves and/or shikanes( to limit the speed and thus risk for the participants). I have a pyrometer not specifically designed for tires but should measure the temp of a tire in several spots. I was typically running circa 2,5 atm (ca 36.7 psi), but never actually measured tyre temperature. I am not sure I am yet good enough foe this ti make too much of a difference, though holding in curves is very important as this is where one may loose a lot of time just because the tires just will not grip well enough. So the pressures may be higher than you might expect.Ĥ00 quid is a bit much for the racing I do. Optimum pressures for my Porsche 993RS are 34 / 38 psi hot. Do let us know how you get on and what pressures you determine are appropriate for your car.īTW. I have some notes from the competitions manager of Toyo UK with some additional details about the care and use of the 888R radial, I will try to find them. ![]() It is very easy to wear all the tread from an overheated 888 in around 20 mins. A word of caution, if you feel the tires go "greasy" and start sliding around, back off and let them cool down. I would start with the tires pressures around 28 - 30 psi (hot) and work from there. ![]() Temperatures whilst out on track are obviously considerably higher. I use Toyo 888R on my Porsche, I usually see temperatures in the mid 60s, following a cool down lap, responsible pit lane entry and parking. If the temperature is significantly higher or lower in the middle, compared to both edges, the pressure should be adjusted. You may find a definite temperature gradient across the tires, high on the inside edge to low on the outside. Obviously you will have to adapt the basic principle to a track day environment. There is a good outline of the procedure Guy mentions in this previous thread.
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