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Watch the TPC code for replacement tires

25K Miles on them, thought I had another 5K to go based on the wear bars. Didnt notice the inside edge wear. Always run at 32PSI, may bump that up to 35PSI to get some more center on the ground. Also going to have the aligment checked, drives and feels fine, but could have a bit excessive negative camber.
 
I will contribute my 2 cents to this discussion. Actually is more like $3000 in tires YTD. I will provide my data, my analysis and let you decide how to adjust your tire pressure to road course HPDE events ...

Vehicle - CT4V-BW
Mileage - 11,600
Track time - 15 days which is about 90 - 20 minute sessions, yielding a total approx track time of 30 hours.
Track miles - that is a tuff one to calculate since I have not been keeping an accounting.
My Best guess is 120 to 150 miles per day = about 2,250 miles.
Tires used - Original set + 3 sets of fronts and 2 sets of rears
Track days per set of front tires = 3 to 4

Issue: Wearing the outside tread block and 1 inch shoulder of tires. Tire tread chunking of outside tire block.

Alignment Configuration - stock for the first 4 track days, then I had a GM Chevy dealer perform the front strut track adjustment per the service manual. They did NOT do a track alignment as I had asked. After another 2 track days, I performed the front suspension bolt adjustment to the suspension to the max. I assume that the camber settings is around -2.5 to -2.7 camber currently.
Tire wear assessment - Tire wear improved after i performed the front suspension bolt adjustment, but I was still wearing out the corner tread and sidewall shoulders of the front tires.

Below is a picture of the second set of fronts. Notice the 1 inch on shoulder wear. They had about 2 track days on them when this picture was taken. The Falken Zenis FK510 lasted 5 or 6 track days. But they were not as good as the Michelins for grip. So I went back to Michelins for my fourth set.

1694633972287.png



I then received information from the Texas V-Club and it was confirmed by Michelin, that if you track your car and run at high speeds, you need to INCREASE the PSI to run near the max pressure when tires are hot.

Proof of concept (POC) - For the last two track sessions, I have started with cold pressures of 42 on all four. I then monitored the PSI during my multiple runs. I hit 48 and 49 Hot tire pressures consistently. I will let out 1 PSI to stay at 48 max for the next session. I will probably start at 41 going forward. The result is a much better shoulder tire wear result. Running in this config for 2 track days I have not had my wear on the shoulders of the tires.

FYI (part1) - regarding the difference between the TPC versus regular Michelin PS 4S:
TPC spec tires-
1694624436532.png


FYI (Part 2) - Per the CT4V-BW Owners Manual:
" Tire Inflation Pressure for Track Driving
For driving on a race course, if your vehicle is equipped with 255/35ZR18 (94Y) and 275/35ZR18 (99Y) tires, set
cold (stationary) tire pressures to 30 psi. During track sessions, set the pressures at 35 to 38 psi for hot tire
pressures. If pressures exceed 38 psi, bleed pressures down to 35 to 38 psi. Return the tires to the recommended
cold tire inflation pressure when track driving has ended."

"Warning: Track/course loads wear tires both on the tread and internal to the tire. When driven in track/course
conditions, even if tread is not worn down to the treadwear indicator, tires must be replaced after the equivalent of two tanks of fuel or approximately 160 km (100 mi)."

Based on the guidance in the Owners Manual, you need to replace all four tires about every track day!

FYI(Part 3) - Page 372 gives conflicting info on "track event" tire pressure guidance.
1694623713755.png


Analysis: Based on information from the Michelin V-CLUB teleconference - "If you are wearing the shoulder of the tire, they are under inflated", and my POC results; I will set the tires pressures for Road Course HPDE events at 41 to 42 PSI and monitor the pressures during track day sessions to ensure that I do not exceed 48 PSI. Max rated PSI is 50.

Also, I would never run @ a event with tires that were cording. The most I would tolerate is about 25% chunking of the outer thread block before I would replace the tires. I will routinely hit 120 to 130 at my "home track". You are seriously risking your safety and those of the other participants if you are on track with known faulty tires.

This picture below shows what was happening to my tires, but I replaced them way before the tires got to this stage, 100% chunking of the outer tread block. If you compare my wear pattern from the top picture, it included wear on the shoulder/sidewall of the tire. These BMW M4 tires are losing half the outer tread block, but there is no wear on the shoulder/sidewall of the tire.

1694635677647.png
 

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jodakid69 said:
I will contribute my 2 cents to this discussion. Actually is more like $3000 in tires YTD. I will provide my data, my analysis and you decide ...

Vehicle - CT4V-BW
Mileage - 11,600
Track time - 15 days which is about 90 - 20 minute sessions, yielding a total approx 30 hours of track time.
Track miles - that is a stuff one to calculate since I have not been keeping an accounting.
My Best guess is 120 to 150 miles per day = So about 2,250 miles.
Tires used - Original set + 3 sets of fronts and 2 sets of rears
Track days per set of front tires = 3 to 4

Issue: Wearing outside shoulder of tires. Outside treat block and 1 inch shoulder of tire. Tire thread chunking of outside tire block.

Alignment Configuration - stock for the first 4 track days, then I had a GM Chevy dealer perform the front strut track adjustment per the service manual. They did NOT do a track alignment as I had asked. After another 2 track days, I performed the front suspension bolt adjustment to the suspension to the max. I assume the settings is around -2.5 to -2.7 camber.
Tire wear assessment - Tire wear improved but I was still wearing out the corner tread and sidewall shoulders of the front tires. I then received information from the Texas V-Club and it was confirmed by Michellin, that if you track your car and run at high speeds, you need to INCREASE the PSI to run near the max pressure when tires are hot.

Proof of concept (POC) - For the last two track sessions, I have started with cold pressures of 42 on all four. I then monitored the PSI during my multiple runs. I hit 48 and 49 Hot tire pressures consistently. I will let out 1 PSI to stay at 48 max for the next session. I will probably start at 41 going forward. The result is a much better shoulder tire wear result. Running in this config for 2 track days I have not had my wear on the shoulders of the tires.

FYI (part1) - regarding the difference between the TPC versus regular Michelin PS 4S:
TPC spec tires-
View attachment 21733

FYI (Part 2) - Per the CT4V-BW Owners Manual:
" Tire Inflation Pressure for Track Driving
For driving on a race course, if your vehicle is equipped with 255/35ZR18 (94Y) and 275/35ZR18 (99Y) tires, set
cold (stationary) tire pressures to 30 psi. During track sessions, set the pressures at 35 to 38 psi for hot tire
pressures. If pressures exceed 38 psi, bleed pressures down to 35 to 38 psi. Return the tires to the recommended
cold tire inflation pressure when track driving has ended."

"Warning: Track/course loads wear tires both on the tread and internal to the tire. When driven in track/course
conditions, even if tread is not worn down to the treadwear indicator, tires must be replaced after the equivalent of two tanks of fuel or approximately 160 km (100 mi)."

Based on the guidance in the Owners Manual, you need to replace all four tires about every track day!

FYI(Part 3) - Page 372 gives conflicting info on "track event" tire pressure guidance.
View attachment 21731

Analysis: Based on information from the Michelin V-CLUB teleconference - "If you are wearing the shoulder of the tire, it is under inflated", and my POC results; I will set the tires pressures for Road Course HPDE events at 41 to 41 PSI and monitor the pressures during track day sessions to ensure that I do not exceed 48 PSI. Max rated PSI is 50.

Also, I would never run on track @ 135+ with tires cording. The most I would tolerate is about 25% chunking of the outer thread block before I would replace the tires.
Click to expand...
Stellar write-up from someone with legit experience. Someone mark this as one of the forum gold nuggets!

Or perhaps cross-post it in the track section of the forum?
 
I'll add some data from the 5BW. My car has had a few different variations of the track alignment, and is currently at -2.5 deg front and -1.8 deg rear camber with 0.1 deg total toe in front and 0.2 deg total toe in rear. I had to go with aftermarket toe links to get enough rear camber as the stock setup was limited to around -1.3 deg camber and still get the desired toe in.

I don't let me car hit the track without the PDR running and I have a macro I run that extracts key data from each run and puts them in a spreadsheet. The result is that I have very good logs on track use.

My first set of fronts lasted 4.2 hours, 346 miles, and 25 total outings on track (some were short and some were longer since I do a lot of open track days). I don't have as good street logs, but as I recall that was around 5000 miles in total including street use. My front camber was really high at that time (>3 deg) and I wore out the insides prematurely so I had to replace them.

My first set of rears have 6.6 hours, 544 miles, and 38 total sessions on track. They also had nearly 10K miles on them in total. They are getting close to the wear bars at this point, but they have worn evenly. Unfortunately, they heat cycled out badly somewhere around 5-6 hours of track time and became very difficult to drive with newer front tires.

This last track event, I switched to new rear tires, and started with that second set of fronts. The second set of fronts has around 5K total miles, 3.3 hours, 270 miles, and 18 sessions of track time on them. They still have decent tread, but I feel like they are starting to fall off a bit from heat cycling.

Overall, I am really impressed with how well the stock tires grip and how long they last.

I will disagree with my friend jodakid on the tire pressures. The manual states the following, which is what I have been doing for all of my track usage and is also consistent with track tire pressures from other vehicles with Michelin tires. The "tire pressures for high speed operation" that jodakid listed above is for things like cruising down the autobahn. While those high pressures may help preserve the shoulder, it is going to add a lot of spring rate to the car and will be very suboptimal for grip.

1694646567041.png
 
dstewart51 said:
Time for tires, cant find the TPC spec for the front locally, dont have time to wait for the TPC spec tires to come in so going to have to put a set of aftermarket PS4S's. I'm sure the new aftermarket 4s's will still feel better than the old warn out OEM's.

View attachment 21722
Click to expand...

ODDLY, I had to trash my tires and get a new set earlier this year for the EXACT same reason - separation between the inner sidewall and tread face. I had been checking the tread face at every gas stop (meaning every other day) and never saw this issue creep up on me. Ended up with a flat - fortunately while in a slow suburban setting (and fortunately I had a set from Costco with the TPC codes sitting in my garage for contingency - I always keep a spare set since I track the car on occasions.)
 
poor-sha said:
I'll add some data from the 5BW. My car has had a few different variations of the track alignment, and is currently at -2.5 deg front and -1.8 deg rear camber with 0.1 deg total toe in front and 0.2 deg total toe in rear. I had to go with aftermarket toe links to get enough rear camber as the stock setup was limited to around -1.3 deg camber and still get the desired toe in.

I don't let me car hit the track without the PDR running and I have a macro I run that extracts key data from each run and puts them in a spreadsheet. The result is that I have very good logs on track use.

My first set of fronts lasted 4.2 hours, 346 miles, and 25 total outings on track (some were short and some were longer since I do a lot of open track days). I don't have as good street logs, but as I recall that was around 5000 miles in total including street use. My front camber was really high at that time (>3 deg) and I wore out the insides prematurely so I had to replace them.

My first set of rears have 6.6 hours, 544 miles, and 38 total sessions on track. They also had nearly 10K miles on them in total. They are getting close to the wear bars at this point, but they have worn evenly. Unfortunately, they heat cycled out badly somewhere around 5-6 hours of track time and became very difficult to drive with newer front tires.

This last track event, I switched to new rear tires, and started with that second set of fronts. The second set of fronts has around 5K total miles, 3.3 hours, 270 miles, and 18 sessions of track time on them. They still have decent tread, but I feel like they are starting to fall off a bit from heat cycling.

Overall, I am really impressed with how well the stock tires grip and how long they last.

I will disagree with my friend jodakid on the tire pressures. The manual states the following, which is what I have been doing for all of my track usage and is also consistent with track tire pressures from other vehicles with Michelin tires. The "tire pressures for high speed operation" that jodakid listed above is for things like cruising down the autobahn. While those high pressures may help preserve the shoulder, it is going to add a lot of spring rate to the car and will be very suboptimal for grip.

View attachment 21740
Click to expand...

Data is life. Thanks for posting all your insight.
 
TPC Spec or not, coming off a worn out set to a new fresh set of rubber feels fantastic. It is truly amazing how much quieter, smoother and more precise the turn in is with the new set. Like putting on a brand new pair of socks, it makes you wish you could put on a new pair every single day.

Today, I had to work up on Mt Wilson, so the new set of PS4S's got a proper break-in, and it was wonderful.
 
I'll lay money down that you can't tell the difference between a specific TPC spec and any other TPC spec on your car.
We run several different tires on our cars, and after competing in cars since 1973, I can't tell the difference. Maybe on a track where you can time small differences in speed, but even then the difference wouldn't be statistically significant.

I have a set of PS4S's on the wife's car, and a set of 200 tw Yokohama's on mine, and other than additional grip, you probably wouldn't know what tire was on the car.

Two more sets of PS4S's in the bags.
 

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I need to download some pics to add to this thread because I had a flat last week and my tire wear shocked me... I purchased 4 new tires and had an alignment..Stand by for pics..
 
Tall Steve said:
I need to download some pics to add to this thread because I had a flat last week and my tire wear shocked me... I purchased 4 new tires and had an alignment..Stand by for pics..
Click to expand...
What kind of mileage did you get? What did you replace them with (TPC spec or regular aftermarket)?
 
Huh...come to think of it, I wonder if I ever had an alignment before my tires shredded like that?? I had similar toe issues on my 5BW. We might need to get these things aligned as soon as they come off the transporter. Will be interesting to see if my newer set of tires after alignment have the same problem.
 
I had the exact same separation on my 5BW and similar toe challenges - makes me think the car may have been misaligned coming off the truck:

1695066976613.jpeg
 
I replaced mine with non TPC spec, just regular aftermarket PS4S's. I cant say if it was due to the OEM tires being warn our not, but the new tires are super quiet, much quieter than I recall the OEM tires being even when new, also turn in is way faster. Could just be because they are new vs old and warn, but I don't recall the OEM tires being either as sharp or quiet. They feel great.
 
A pothole made a nasty cut into the sidewall of a front tire. Its been ordered as a free replacement due to tire & wheel insurance. I made certain to tell them it needs to be a matching TPC spec.
 
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