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Discussion Starter #1
After spending some time searching around for both cold and hot tire pressures for RA1s, I've decided to start a thread with the 'official' numbers.

I'll be running 8 sessions over the weekend. I have a probe type pyrometer which I'll be using after each session and recording the results.

Right now my tires are at 26 front and 36 rear. :eek: This is 45 minutes to 1 hour after driving 120 miles to Texas World Speedway in College Station with the car sitting in the parking lot at the hotel in 65 degree weather.

I've seen all kinds of numbers while searching. Since I left all my previous measurements at home, I wanted to get an idea of where to start... I've seen everything from 21 to 40+. That's a pretty wide range.

If you have a good idea on starting pressures (show up at the track in the morning and set your tires to X front and Y rear then adjust from there), please feel free to post them.
 

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Discussion Starter #2
It's 61 this morning with a high of 78 today according to weather.com.
 

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Discussion Starter #3
I talked to two very experienced Elise drivers with LOTS of experience with RA1s. One keeps extensive notes of each session and suggested a starting pressure of 28 front and 26 rear, cold. The other suggested starting pressures of 30 each and then working from there.

I've decided to start with 30 in each tire cold.
 

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Discussion Starter #4
Session 1:

Tire Pressure after cool down lap and 1 minute to parking spot:
LF: 34.5 RF: 34.5
LR: 35.5 RR: 35

Tire temps
LF: 127 136 125 RF: 131 135 127
LR: 135 140 144 RR: 150 142 136

Notes: One spin, came into carousel too fast and got the back end out a bit.

Based on the above temps I'm dropping the fronts by 1 lb each.
 

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RichS,
can you try getting the pressure and temps after a hot lat? If not, try to run the cool down lap as fast and as consistent as possible without using the brakes. That way, you can try ensuring that the tires reach their operating temperature.
 

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Discussion Starter #6
Session 2:

Tire Pressure after cool down lap and 30 seconds to parking spot:
LF: 34.5 RF: 34.5
LR: 36 RR: 36

Tire temps:
LF: 141 146 136 RF: 141 149 140
LR: 145 151 155 RR: 163 155 145

Notes: No spins, 1.5 seconds a lap faster

Based on the above temps I'm dropping the fronts by another lb each

Ambient temperature has risen by about 10 degrees.
 

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Agree w/ MyElise. My comfort level has always been 28F/30R hot pressures. I find anything above 30 to be slippery.

I haven't tried going 40 hot like many here likes to do.
 

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Discussion Starter #8
Session 3:

Tire Pressure after cool down lap and 30 seconds to parking spot:
LF: 34.5 RF: 34.5
LR: 37 RR: 37

Tire temps:
LF: 144 152 142 RF: 150 157 140
LR: 151 154 155 RR: 166 160 151

Notes: No spins, .9 seconds slower on best lap, lots of traffic, everything FELT faster, but the data doesn't lie, only two sectors are the fastest of the day.

Based on the above temps I'm dropping the fronts by another 2 lbs each
 

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Discussion Starter #9
You're about 6 lbs. high in all 4.
Really? Why do you say that? The rears are relatively linear, the fronts definitely have too much pressure though.
 

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Discussion Starter #10
Session 4:

Tire Pressure after cool down lap and 30 seconds to parking spot:
LF: 32.5 RF: 33
LR: 37 RR: 36.5

Tire temps:
LF: 147 153 152 RF: 153 157 146
LR: 153 158 159 RR: 167 163 152

Notes: No spins, .4 seconds slower on best lap of previous session, things felt good. Ambient temperature was maybe 5 degrees warmer.

Based on the above temps I'm dropping the fronts by another 1 lbs each. We'll see how it goes tomorrow.
 

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Discussion Starter #11
Based on discussion during dinner with other Lotus drivers, the general consensus seems to be that even the rears are high because the temps should be a bit cooler than 37 'hotish'.

In the morning I'll be going with 26 lbs in the front and 25 lbs in the rear and see what happens from there.
 

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I like 25.5F 26R hot...I think next time I go out I'll try something on the high end like near 35 and see what happens, I just remember it being a little funky when too high.
 

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Discussion Starter #13
Pre-first session:

All pressures at 26, ambient temp is 64.
 

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Discussion Starter #14
Session 5 (day 2):

Tire Pressure after cool down lap and 15 seconds to parking spot:
LF: 30 RF: 30
LR: 30.5 RR: 30.5

Tire temps:
LF: 135 143 135 RF: 141 149 138
LR: 139 145 145 RR: 160 151 141

Notes: No spins, .5 seconds slower than the best lap yesterday. The car actually felt better, it felt like I had more grip in the corners.

Based on the above temps I'm dropping the fronts by 2 lbs each.
 

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Discussion Starter #15
Session 6 (day 2)

Tire Pressure after cool down lap and 15 seconds to parking spot:
LF: 28 RF: 28
LR: 30 RR: 30

Tire temps:
LF: 132 137 131 RF: 136 145 131
LR: 134 138 138 RR: 149 142 132

Notes: Spun coming out of 4. Car feels good. I rode with an instructor in the previous session so I was trying a few different things (including more speed into 4), best time increased by .8 seconds.

Not sure if I should go lower on the fronts or not. I'm going to do one lb less and see how it goes. I definitely have more grip through the carousel today than I did yesterday, especially towards the end of the session.

Based on the above temps I'm dropping the fronts by 1 lbs each.
 

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Discussion Starter #16
Session 7 (day 2)

Tire Pressure after cool down lap and 15 seconds to parking spot:
LF: 28 RF: 28
LR: 30 RR: 30

Tire temps:
LF: 142 147 140 RF: 152 151 141
LR: 143 147 148 RR: 157 154 145

Notes: No spins. Car felt very stable. Slight misting rain before session. I think I've found the ideal pressure for me. 1.3 seconds off of fastest lap from earlier today (mist on track)
 

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Discussion Starter #17
Session 7 (day 2)

Tire Pressure after cool down lap and one minute to parking spot:
LF: 28 RF: 28
LR: 30.5 RR: 30.5
Tire temps:
LF: 136 146 130 RF: 147 151 139
LR: 134 143 138 RR: 157 145 141

Notes: No spins. Car felt very stable. Slight misting rain before session. 1 second dropped from previous fastest lap from earlier today (mist at the end of session)

Not sure if the temps really indicate that I've got too much pressure. Ambient temp has been consistently 74 throughout the day (first session was colder).
 

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It starting to look like using the factory tire pressure recommendations (even if they're for a different tire) would have been a good place to start!

Yes, tire construction, sidewall stiffness and tread belts differ from tire brand/model, but ultimately the tire is a big balloon that is reacting to loads created by the mass of the vehicle. So, one could deduce that stock pressures might be a good starting point.

Cheers,
Kiyoshi
 
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