Hi Everyone,
Thanks for posting our video and sharing well-thought-out commentary. It's much appreciated. I believe Tesla is looking into the issue that we experienced on the track with the Plaid, and hopefully it is something that would only ever occur when stability control is disabled. I wish we had time to validate that at the track when we were there.
We'll of course keep you updated as things progress. Sadly there is snow on the ground here now, so we're benched for the time being. Thank you so much to Chad and Andrew from TeamPGR for being incredible development partners through that stressful moment. We're really fortunate that the only damage was a cracked front plastic undertray. Not even a scratch on the car thanks to the wet ground!
I wanted to address wheel size in regards to my earlier comment. Two points:
#1 - Tire diameter (forget about sidewall for a moment), leads to more grip. Wider is better, and taller is better too. Especially in the case of such a heavy car, you basically cannot fit a tire that is "too large". The comment I made suggesting that no one that was looking for serious performance would consider a 19" wheel, was made specifically due to the diameter that 19" tires are available in. The OE 21" Plaid tires are 720mm in diameter in the front, and 740mm in the rear.
These are TALL tires! No doubt chosen for a reason, as that helps with longitudinal acceleration. Something the Plaid needs all the help it can get to put down 1000hp!
While the Plaid doesn't suffer from the same kind of high-rpm power dropoff that the Model 3 does (thank you carbon-sleeved rotors!), it is still optimal for grip and motor efficiency to keep as much diameter there as you can.
The 315/30/20 tires we are using at this point are 700mm in diameter, and that is about as small as I would want to go. I would prefer to use a taller tire to be honest, and it is something we're looking into. It's just difficult as some of the OEM special tires have more grip than the generic counterparts, and right now we are using a Ford Performance variant that we think might be an advantage.
When we look at tires in the 700+ diameter in 19's, you'll see that there are not many options:
A quick glance (there could be mistakes) shows the following at or above 700mm in diameter:
PS4S - 275/40/19 is the only size listed at or above 700mm
Pilot Sport Cup 2 - nothing
Eagle F1 Supercar 3R - nothing
Trofeo R - nothing
Kumho V720 - Hope you can fit 355's!
RE71R - nothing
Tires are worth so much lap time, that any thinking about a pound or two of unsprung mass is nothing compared to fitting the optimal size tire. LMP1 cars use tires that are 710mm in diameter, and they only weigh 1900lbs! Every time we've moved to a larger diameter tire on our racecar (which is now running GTD lap times, with GTD levels of power), we've seen a big step up in performance. If you look at other GT3 cars, you'll see that they all run extremely tall tires in comparison to their factory counterparts. This is not by mistake.
Since we're talking about a car with tons of power and weight, it will overheat the tires quickly - so the larger the tire, the more rubber you have to average that load over, and thus the cooler the tire will run - or the longer it will go before it feels like it's melting underneath you.
#2 - If you still want 19's (tires are cheaper!), I'm happy to report that with our 400mm BBK we have over 16mm of clearance to the 20" Martian wheel that is on the car now, meaning a 19" would most likely fit (1/2" = 12.7mm). We also just test fit an Advan RGIII 19" wheel and it appears to have ample clearance (around 10mm). So if you want to use 19's, it is most likely not a problem to do so as long as you find wheels with a lot of barrel clearance.
If I could make the rotors even larger, I would do that. Ultimately getting the brakes to work and last for a few laps is the most important thing and a 1000hp car with the one of the lowest drag coefficients on the market is putting SO much heat into the brakes, it's really hard to overstate it. The stability / traction control are doing nothing compared to the raw power.
To put it in perspective, at the local track from the video, the Plaid is slowing a 5000lb car (including driver) from 240km/h to 130km/h, whereas an AWD Model 3 is slowing a 4200lb car from 190km/h to 130km/h. That's something like 2.5 times the amount of energy going into the brakes/battery.
Before the snow fell I experimented with flexing the OEM anti-drag springs, and it appears that they can be yielded (bent) to a point where they will stop the pad rattle but still make a difference to pedal feel.
I had bent them too far, so there was still some light pad rattle, but the pedal feel from the prototype pads, rotors, and removal of that "dead zone" was incredible. The brakes actually feel GOOD. Not just average, but I would say good. They weren't perfect but if you went from the current pedal feel to this, I'm pretty sure no one would ask for anything more!
Now if we can just get this ABS fixed and the snow off the ground for one more test... Originally we had an optimistic goal of a 1:14, but I now feel like a 1:13 would be possible. I did a 1:15.2 on a very careful lap after the brake failure, and without talking about improving the restrictive exits - I was leaving at least 1.5 seconds on the table in braking (for obvious reasons!).
For a street tire that must be some kind of record at this small little track. There was a time not too long ago when a 1:15 on slicks was very fast. IMSA GT4 cars would do a 1:14-1:15 around this track not too long ago when they were using Continental tires. I currently hold the RWD lap record with our Time Attack 350z car with a 1:09 - and that is with brand new prepped slicks, so it gives you an idea of how fast a 1:13 is.
Thanks for posting our video and sharing well-thought-out commentary. It's much appreciated. I believe Tesla is looking into the issue that we experienced on the track with the Plaid, and hopefully it is something that would only ever occur when stability control is disabled. I wish we had time to validate that at the track when we were there.
We'll of course keep you updated as things progress. Sadly there is snow on the ground here now, so we're benched for the time being. Thank you so much to Chad and Andrew from TeamPGR for being incredible development partners through that stressful moment. We're really fortunate that the only damage was a cracked front plastic undertray. Not even a scratch on the car thanks to the wet ground!
I wanted to address wheel size in regards to my earlier comment. Two points:
#1 - Tire diameter (forget about sidewall for a moment), leads to more grip. Wider is better, and taller is better too. Especially in the case of such a heavy car, you basically cannot fit a tire that is "too large". The comment I made suggesting that no one that was looking for serious performance would consider a 19" wheel, was made specifically due to the diameter that 19" tires are available in. The OE 21" Plaid tires are 720mm in diameter in the front, and 740mm in the rear.
These are TALL tires! No doubt chosen for a reason, as that helps with longitudinal acceleration. Something the Plaid needs all the help it can get to put down 1000hp!
While the Plaid doesn't suffer from the same kind of high-rpm power dropoff that the Model 3 does (thank you carbon-sleeved rotors!), it is still optimal for grip and motor efficiency to keep as much diameter there as you can.
The 315/30/20 tires we are using at this point are 700mm in diameter, and that is about as small as I would want to go. I would prefer to use a taller tire to be honest, and it is something we're looking into. It's just difficult as some of the OEM special tires have more grip than the generic counterparts, and right now we are using a Ford Performance variant that we think might be an advantage.
When we look at tires in the 700+ diameter in 19's, you'll see that there are not many options:
A quick glance (there could be mistakes) shows the following at or above 700mm in diameter:
PS4S - 275/40/19 is the only size listed at or above 700mm
Pilot Sport Cup 2 - nothing
Eagle F1 Supercar 3R - nothing
Trofeo R - nothing
Kumho V720 - Hope you can fit 355's!
RE71R - nothing
Tires are worth so much lap time, that any thinking about a pound or two of unsprung mass is nothing compared to fitting the optimal size tire. LMP1 cars use tires that are 710mm in diameter, and they only weigh 1900lbs! Every time we've moved to a larger diameter tire on our racecar (which is now running GTD lap times, with GTD levels of power), we've seen a big step up in performance. If you look at other GT3 cars, you'll see that they all run extremely tall tires in comparison to their factory counterparts. This is not by mistake.
Since we're talking about a car with tons of power and weight, it will overheat the tires quickly - so the larger the tire, the more rubber you have to average that load over, and thus the cooler the tire will run - or the longer it will go before it feels like it's melting underneath you.
#2 - If you still want 19's (tires are cheaper!), I'm happy to report that with our 400mm BBK we have over 16mm of clearance to the 20" Martian wheel that is on the car now, meaning a 19" would most likely fit (1/2" = 12.7mm). We also just test fit an Advan RGIII 19" wheel and it appears to have ample clearance (around 10mm). So if you want to use 19's, it is most likely not a problem to do so as long as you find wheels with a lot of barrel clearance.
If I could make the rotors even larger, I would do that. Ultimately getting the brakes to work and last for a few laps is the most important thing and a 1000hp car with the one of the lowest drag coefficients on the market is putting SO much heat into the brakes, it's really hard to overstate it. The stability / traction control are doing nothing compared to the raw power.
To put it in perspective, at the local track from the video, the Plaid is slowing a 5000lb car (including driver) from 240km/h to 130km/h, whereas an AWD Model 3 is slowing a 4200lb car from 190km/h to 130km/h. That's something like 2.5 times the amount of energy going into the brakes/battery.
Before the snow fell I experimented with flexing the OEM anti-drag springs, and it appears that they can be yielded (bent) to a point where they will stop the pad rattle but still make a difference to pedal feel.
I had bent them too far, so there was still some light pad rattle, but the pedal feel from the prototype pads, rotors, and removal of that "dead zone" was incredible. The brakes actually feel GOOD. Not just average, but I would say good. They weren't perfect but if you went from the current pedal feel to this, I'm pretty sure no one would ask for anything more!
Now if we can just get this ABS fixed and the snow off the ground for one more test... Originally we had an optimistic goal of a 1:14, but I now feel like a 1:13 would be possible. I did a 1:15.2 on a very careful lap after the brake failure, and without talking about improving the restrictive exits - I was leaving at least 1.5 seconds on the table in braking (for obvious reasons!).
For a street tire that must be some kind of record at this small little track. There was a time not too long ago when a 1:15 on slicks was very fast. IMSA GT4 cars would do a 1:14-1:15 around this track not too long ago when they were using Continental tires. I currently hold the RWD lap record with our Time Attack 350z car with a 1:09 - and that is with brand new prepped slicks, so it gives you an idea of how fast a 1:13 is.
