The Lotus Cars Community banner

1 - 16 of 16 Posts

·
Registered
Joined
·
3,520 Posts
Discussion Starter #1
first track day with the car tomorrow. I'm just sondering what the operating temperature is for these tires that I should be looking for. Thanks.
 

·
Registered
Joined
·
138 Posts
I've been running at 26 front/27 rear hot. I've got 4 days out of the rears (possibly could have pushed it one more day but decided to play it safe) and im crossing my fingers i'll get at least 7 out of the fronts.

Have fun!!!
 

·
Registered
Joined
·
6,981 Posts
reemo said:
I've been running at 26 front/27 rear hot.
Uh... that isn't a temperature.

xtn
 

·
Registered
Joined
·
337 Posts
I've done some digging on this, although I'm not sure I have an answer :confused:

Last weekend, I was with a friend and his new Exige for his first time at the track. Armed with tire pressure gauge and tire probe pyrometer, we were trying to get setup right and noticed that when the car was running at about 27/29psi HOT pressures, tire temperatures were only in the 120s F for front wheels and 130s F for rear wheels. Ambient was about 70F. For reference, rears were hottest on the inside, fronts on the outside - front camber is maxed out. Front center temps were maybe 5F less than average of outside and inside, implying more pressure needed. But read on:

The low tire temps set me thinking, since normally R-Compound tires need to be in the range 160F to 220F to work properly. Tire Rack has some great spec sheets on this - it varies between tires, some have a narrower range than others, but generally the range above is a good one.

Obviously, 120F to 130F wasn't going to do it - and this squared with both of us feeling that the tires weren't really hooking up properly. We were not exactly overwhelmed with the A048s as R-Compound tires :rolleyes: Both of us instruct for a range of car clubs, so we were running the car fairly hard - it isn't a case of we just need to go faster :D At least, I hope not!

I called Yokohama, and they put me on to their track service guys at TrackSidePerformance, who gave two data points. First, they confirmed that to work the A048s properly, you need to get closer to 200F, second, they thought that more toward 30psi was the best pressure.

Now :wallbang: the problem is that we can't figure out HOW in the world to get the Exige to heat its tires up toward 200F. Its just too lightweight a car. First thought is to try running MUCH lower pressures with the idea that resultant flex would induce some heat - anyone tried this? Has anyone else got any input on the tire temperature thing?
 

·
Registered
Joined
·
6,981 Posts
The highest probe reading I got on my A048 rears was 137. That was with 95F ambient. It was my first HPDE though. Not very fast at all. Beginner group. I hope to take a reading on YAUDI's tires on Monday. He's reasonably fast enough to get the tires up as much as their going to get up, although I only expect 70F ambients. I'll report back next week.

Edit: I just remembered he doesn't have his Yokos on any more. Oh well there will be plenty of Elise/Exige at the event. I'll get some data points.

xtn
 

·
Registered
Joined
·
3,520 Posts
Discussion Starter #6 (Edited)
alright guys I'm at the track and finding some interesting things, for one, TC does seem to be getting in the way of putting down power on turn exit.. Stock brake pads do seem to fade off a little bit. Understeer is prevelent. Other than that its a blast and I find it rather easy to drive pretty quick, While I'm far from really pushing it I'm going quicker than I thought first day with it.

last time out my temps were: (inside/middle/outside)
LF: 144/143/161
RF: 134/131/143
LR: 170/164/171
RR: 167/157/158
ambient: ~75 I think

I'm going clockwise on Streets of Willow.

I'm using throttle and intentional lifting to help control the understeer. I actually kind of prefer it for the first time out, its a little safer. Mounting a transpander shortly so I'll start getting times.

I did notice once I started to get those rears closer to 200 I was able to lay into throttle a bit more but the front is still pushing a bit.

Oh ya, I've settled on 24 pounds front and 27 rear hot. Might be low but I think its helping with the understeer and it is seeming to help increase temp overall i nthe tires.

I stil lhavn't seen the coolant break 200! Thats awesome coming from an regularly HOT turbo Miata that I was used to.
 

·
Registered
Joined
·
888 Posts
This topic merits discussion. Thanks for floating a thread on it. :clap:

Me, I've been meaning to actually use my pyrometer, but I've yet to get around to it. The data's interesting to me both because it's a way (i) to get some sense of the temperatures I'm generating (curiosity) and (ii) to assess whether the hot temperatures recommended on the boards and by Lotus Motorsports (26f/29r) generate relatively even temps across the tire (and, by association, whether my camber settings are working the tires efficiently).

The first question -- what absolute temperatures I'm generating -- is interesting, as it speaks to whether or not the A048s are appropriate for the light weight of the car. I confess that I've not found them as grippy as I'd have expected, but then again I have likely heat cycled mine after 8 events, particularly in the back (the car's gotten increasingly tail-happy; the rears have worn well past the tread indicator bars to the point where they're esssentially slicks).

I look forward to the rest of this discussion. If anyone has tire temperatures/pressures AND camber settings, pls. share both sets of data. Thanks.

Twin
 

·
Registered
Joined
·
3,520 Posts
Discussion Starter #8
I will also say that I have one camber shim + the bracket on each side. Thats how mine came. I decided to leave it for the first event to baseline it. Everything is bone stock besides harness bar and harnesses.

I'm writing down temps of mine and my dads runs and I've got video of most of them. The transponder is on the car and I'll start timing laps after lunch. It'd be interesting to see if these cars are just too light for these tires, I wouldn't think Lotus would do that but you never know.
 

·
Registered
Joined
·
613 Posts
Evil Twin said:
This topic merits discussion. Thanks for floating a thread on it. :clap:


The first question -- what absolute temperatures I'm generating -- is interesting, as it speaks to whether or not the A048s are appropriate for the light weight of the car. I confess that I've not found them as grippy as I'd have expected, but then again I have likely heat cycled mine after 8 events, particularly in the back (the car's gotten increasingly tail-happy; the rears have worn well past the tread indicator bars to the point where they're esssentially slicks).



Twin
Interesting question. I think that the SCCA Spec Racer Ford class, while somewhat of a tank but still lighter than an Elise, was running A048s.
 

·
Registered
Joined
·
1,372 Posts
starting pressure 26 front/29 rear
hot pressure 29.5 front, 33.5 left rear/34 right rear

temp readings:

left front rt front
151 154 149 139 158 166


left rear rt rear
156 151 174 178 162 166


alignment specs.
camber: front 1.2 L& R
rear 2.6 left, 2.7 rt.

I still have 1 shim left in front rt, none in front left. I'll change that in the future.

Temps were consistently low in the center of the rears, We considered that there might be less frictin on the center due to the tire construction. Yokohama had no answer. I was referred to the race tire distributor. No one answered the phone so who knows. I'm open to different brands in the future
Got 13 heat cycles now and a couple thou of driving. The durometer looked on the high side before running last weekend.

I ran in the Corvette racers series as a guest and did decent. Since they have c5 Z06s that have over twice the whp, I wasn't expecting to do as well as I did. They run anything including Goodyear slicks. My tires were likely as hard as the track! Things should get better with more grip.

A side note, I keep in touch with Kumho, as I ran there stuff a couple years on the Vette. They have sizes that will work for us in the coming months.
It will be in the V710 line. They are softer with a wear number of 30, and they get sticky. That's about the best DOT out there for now. The Hoosier r5's didn't cut it against the Kumhos. The r6 might be closer though.
 

·
Registered
Joined
·
1,519 Posts
I was under the impression that MikeW was running too much air in the rear tires and not enough up front. My car is set up with the same alignment, coincidentally, but 29 or 30 psi hot front and rear. The extra pressure up front gives me less understeer although it's a tough balance given the fact that my front temps are 145 max on the outsides and less pressure would result in more heat and presumably more grip. But less pressure results in sloppy steering I find so I'm staying with 29psi until I get the rears resolved.

The biggest problem is that the rears still heat up more inside (167 in the pits) and the wear bar in the MIDDLE is flush, but not on the edges which would normally indicate too much air. I'm considering adding one shim and dropping pressure to 27 in the rear to even up/increase the temps.

All this info came from running WS Streets CCW ambient temp 60F last weekend. Had similar results few weeks before that at WS Horse Theif, a much tighter track, with ambient temps 70F.

From what I've heard, the V710's wear very quickly like a race slick.
 

·
Registered
Joined
·
890 Posts
I've done quite a few track events with various car clubs as well as racing schools and races with Skip Barber. And I can say with CERTAINTY that based on my driving ability the tire temperature is NOT going to have a major affect on my lap time. My advise is to do 1 to 2 warm up laps and get the rubber up to temperature. If your paces is slow, my guess is that it has more to do with your lines than your ruuber temperature and pressure.
 

·
Registered
Joined
·
1,519 Posts
pchop said:
I've done quite a few track events with various car clubs as well as racing schools and races with Skip Barber. And I can say with CERTAINTY that based on my driving ability the tire temperature is NOT going to have a major affect on my lap time. My advise is to do 1 to 2 warm up laps and get the rubber up to temperature. If your paces is slow, my guess is that it has more to do with your lines than your ruuber temperature and pressure.
I think this is true unless the track and ambient temps are very low. The other issue is getting even heat so that you wear evenly and get max contact in the turns. At neg 2.5 camber rear I'm finding the insides still heat up 10 deg more (167F) than center and outside. Is anyone getting more even temps with les neg camber. If so, does it improve wear and/or traction?
 

·
Registered
Joined
·
1,418 Posts
A few more specifics for people trying to track this. Make up a sheet with a grid pattern of the 4 tires labeled and places to put the temps and pressures. If you don't pull over while still coming off pit road, the measurements will be inaccurate. Best is to have someone standing on the other side of the wall that jumps over and does the reading for you while you are still in the car. Hopefully not getting run over in the process. The infrared pyrometers are considered inferior to the contact ones (have a little needle that goes into the tire).
The car is fairly neutral but you can make it either understeer or oversteer readily by changing the tire pressures, sometimes just a little.
 

·
Registered
Joined
·
1,519 Posts
At Buttonwillow, ambient 80-85F sunny - this is the first time I'm tracking on a 'hot' day and I'm getting 210/195/190 Rear inside to outside. I stopped watching my fronts since the factory camber max is still not enough and they just run cool. THe tire really comes to life at this higher temp range - not as much threat of tail snap when you put the power down on turn exit and noticably stickier on entry. I'd say this is a great summer tire. I was less impressed in cooler weather, but I'm also getting more accustomed to the car and my lines are improving.
 

·
Registered
Joined
·
3,520 Posts
Discussion Starter #16
old thread rehashed. I would agree. Since the thread was posted, but while I still had the A048s, I found them to really come to life at ~200. Noticeably grippier. Thats whats nice about the RA1'a, the come into grip at a much lower temp. and remain grippy. RA1 recomended temp is 160-220 for reference.
 
1 - 16 of 16 Posts
Top