The Tire DB - Posts about Track and AutoX tire brands
01-10-2009, 09:54 PM
#681
Registered User
Join Date: Jan 2009
Location: Seattle
Posts: 12
Likes: 0
Received 0 Likes
on
0 Posts
Since you mentioned it - Pacific Raceways it is 
I have done 3 days there by now and feel like I am ready to start playing with pressure settings. Looks like 42-44 PSI cold is way too much. No wonder I was bouncing like a ball in turn 2
I have done 3 days there by now and feel like I am ready to start playing with pressure settings. Looks like 42-44 PSI cold is way too much. No wonder I was bouncing like a ball in turn 2
01-10-2009, 09:59 PM
#682
The tyres are gonna heat up during the action so as a result, you will have more pressure later on. Steering response is pretty soft at the beginning but as the tyres heat up, they get better. After doing 1 full hour at the track my brand new Invo showed no signs of getting chewed up at the side walls.
Outer patch shows more wear though. Thus the need for camber kit.
btw i live in the middle east and it gets pretty warm here so i need lower tyre pressure
Maybe 37-38 psi front and 35- 37 psi rear is enough for you during the cold season.
good luck!
Last edited by 350Zdj; 01-10-2009 at 10:12 PM.
01-10-2009, 10:06 PM
#684
Registered User
Join Date: Jan 2009
Location: Seattle
Posts: 12
Likes: 0
Received 0 Likes
on
0 Posts
Yes, that's why I mentioned I get 47-49 when heated up. I was not really sure how much is enough. Now, looks like I probably should be running around 35 cold (front), which would bring me to around 42 hot.
01-10-2009, 10:08 PM
#685
Registered User
Join Date: Jan 2009
Location: Seattle
Posts: 12
Likes: 0
Received 0 Likes
on
0 Posts
Funny enough but T8-T9 usually goes pretty smooth. Slippery but smooth. It's T2 where I really start asking myself if my tires are doing good.
01-10-2009, 10:35 PM
#687
Registered User
Join Date: Jan 2009
Location: Seattle
Posts: 12
Likes: 0
Received 0 Likes
on
0 Posts
Check that
Found a good summary on tirerack for adjusting for under/oversteering: http://www.tirerack.com/tires/tirete....jsp?techid=58.
Found a good summary on tirerack for adjusting for under/oversteering: http://www.tirerack.com/tires/tirete....jsp?techid=58.
01-11-2009, 06:03 AM
#689
Since you kinda new at tracking, try this plan for street tires (not R-comps):
Start out in the morning with factory "COLD" tire pressures (likely 35 psi), and then check them ASAP at the completion of each session when you pull back into the paddock. Then let the excess pressure out down to not more than 40 PSI "HOT"....do this after each session.
After you get a better feel for your tires/track/ambient Temps/etc, you will find that you use a COLD STARTING pressure of as low as 30-32 and different front-to-rear and left-to-right pressure differences as suggested below. Or you may find on a really cold day (new freezing) that you may need to have a higher pressure (higher than factory cold pressure recommendations) for the 1st session of the day. For example: I sometimes run LF= 30 psi, RF 32 psi, LR=31, RR=32 on a predominantly "right-turn" track since the LF tire will get hotter than the RF...same goes for the LR tire. It normally gets hotter than the RR, thus the tire pressure will grow at different rates so my starting psi is different, but reach a similar "hot" psi on the track.
I live in Atlanta, GA and we track all year long. So when it is 30 deg in the mornings, my COLD PSI is much different/higher than when it is 90 deg for the 1st track session. But the process of lowering the pressure after each session is the same.
Note: If you are running a 2-day event, you will need to "air-up" the morning of the second day since you will have let so much air OUT of you tires. I might find 2nd day starting PSI as low as 20 PSI before adding back in air.
Start out in the morning with factory "COLD" tire pressures (likely 35 psi), and then check them ASAP at the completion of each session when you pull back into the paddock. Then let the excess pressure out down to not more than 40 PSI "HOT"....do this after each session.
After you get a better feel for your tires/track/ambient Temps/etc, you will find that you use a COLD STARTING pressure of as low as 30-32 and different front-to-rear and left-to-right pressure differences as suggested below. Or you may find on a really cold day (new freezing) that you may need to have a higher pressure (higher than factory cold pressure recommendations) for the 1st session of the day. For example: I sometimes run LF= 30 psi, RF 32 psi, LR=31, RR=32 on a predominantly "right-turn" track since the LF tire will get hotter than the RF...same goes for the LR tire. It normally gets hotter than the RR, thus the tire pressure will grow at different rates so my starting psi is different, but reach a similar "hot" psi on the track.
I live in Atlanta, GA and we track all year long. So when it is 30 deg in the mornings, my COLD PSI is much different/higher than when it is 90 deg for the 1st track session. But the process of lowering the pressure after each session is the same.
Note: If you are running a 2-day event, you will need to "air-up" the morning of the second day since you will have let so much air OUT of you tires. I might find 2nd day starting PSI as low as 20 PSI before adding back in air.
01-11-2009, 07:51 AM
#690
Registered User
Join Date: Sep 2007
Location: DC Metro
Posts: 286
Likes: 0
Received 0 Likes
on
0 Posts
I'm in this ballpark.
I normally start with 35PSI COLD.
Then after my first session, I immediately take a reading of PSI. It's normally 41-42. I normally shoot for 38psi hot, so I would let the pressure out until it reached 37PSI.
Next time out I should be running at 38psi when I'm hotlapping.
It's also a great time to get an IR read of how hot the front rotors are.
I normally start with 35PSI COLD.
Then after my first session, I immediately take a reading of PSI. It's normally 41-42. I normally shoot for 38psi hot, so I would let the pressure out until it reached 37PSI.
Next time out I should be running at 38psi when I'm hotlapping.
It's also a great time to get an IR read of how hot the front rotors are.
01-11-2009, 11:44 AM
#691
Registered User
Join Date: Jan 2009
Location: Seattle
Posts: 12
Likes: 0
Received 0 Likes
on
0 Posts
Thanks to all of you! I was definitely on the wrong side with my higher pressures. Makes perfect sense to keep the contact patch as wide as possible. Next time I will do what you suggest and check it after each session to keep it under 40.
01-11-2009, 02:05 PM
#692
Since you kinda new at tracking, try this plan for street tires (not R-comps):
Start out in the morning with factory "COLD" tire pressures (likely 35 psi), and then check them ASAP at the completion of each session when you pull back into the paddock. Then let the excess pressure out down to not more than 40 PSI "HOT"....do this after each session.
After you get a better feel for your tires/track/ambient Temps/etc, you will find that you use a COLD STARTING pressure of as low as 30-32 and different front-to-rear and left-to-right pressure differences as suggested below. Or you may find on a really cold day (new freezing) that you may need to have a higher pressure (higher than factory cold pressure recommendations) for the 1st session of the day. For example: I sometimes run LF= 30 psi, RF 32 psi, LR=31, RR=32 on a predominantly "right-turn" track since the LF tire will get hotter than the RF...same goes for the LR tire. It normally gets hotter than the RR, thus the tire pressure will grow at different rates so my starting psi is different, but reach a similar "hot" psi on the track.
I live in Atlanta, GA and we track all year long. So when it is 30 deg in the mornings, my COLD PSI is much different/higher than when it is 90 deg for the 1st track session. But the process of lowering the pressure after each session is the same.
Note: If you are running a 2-day event, you will need to "air-up" the morning of the second day since you will have let so much air OUT of you tires. I might find 2nd day starting PSI as low as 20 PSI before adding back in air.
Start out in the morning with factory "COLD" tire pressures (likely 35 psi), and then check them ASAP at the completion of each session when you pull back into the paddock. Then let the excess pressure out down to not more than 40 PSI "HOT"....do this after each session.
After you get a better feel for your tires/track/ambient Temps/etc, you will find that you use a COLD STARTING pressure of as low as 30-32 and different front-to-rear and left-to-right pressure differences as suggested below. Or you may find on a really cold day (new freezing) that you may need to have a higher pressure (higher than factory cold pressure recommendations) for the 1st session of the day. For example: I sometimes run LF= 30 psi, RF 32 psi, LR=31, RR=32 on a predominantly "right-turn" track since the LF tire will get hotter than the RF...same goes for the LR tire. It normally gets hotter than the RR, thus the tire pressure will grow at different rates so my starting psi is different, but reach a similar "hot" psi on the track.
I live in Atlanta, GA and we track all year long. So when it is 30 deg in the mornings, my COLD PSI is much different/higher than when it is 90 deg for the 1st track session. But the process of lowering the pressure after each session is the same.
Note: If you are running a 2-day event, you will need to "air-up" the morning of the second day since you will have let so much air OUT of you tires. I might find 2nd day starting PSI as low as 20 PSI before adding back in air.
01-12-2009, 07:37 AM
#694
Added advice:
Purchase a good racing-type air pressure gauge, and use it exclusively!
Why: If you tested with 5 x tire gauges, you would likely get 5 different readings, so just use one gauge all the time for this tire tuning process.
Purchase a good racing-type air pressure gauge, and use it exclusively!
Why: If you tested with 5 x tire gauges, you would likely get 5 different readings, so just use one gauge all the time for this tire tuning process.
Since you kinda new at tracking, try this plan for street tires (not R-comps):
Start out in the morning with factory "COLD" tire pressures (likely 35 psi), and then check them ASAP at the completion of each session when you pull back into the paddock. Then let the excess pressure out down to not more than 40 PSI "HOT"....do this after each session.
After you get a better feel for your tires/track/ambient Temps/etc, you will find that you use a COLD STARTING pressure of as low as 30-32 and different front-to-rear and left-to-right pressure differences as suggested below. Or you may find on a really cold day (new freezing) that you may need to have a higher pressure (higher than factory cold pressure recommendations) for the 1st session of the day. For example: I sometimes run LF= 30 psi, RF 32 psi, LR=31, RR=32 on a predominantly "right-turn" track since the LF tire will get hotter than the RF...same goes for the LR tire. It normally gets hotter than the RR, thus the tire pressure will grow at different rates so my starting psi is different, but reach a similar "hot" psi on the track.
I live in Atlanta, GA and we track all year long. So when it is 30 deg in the mornings, my COLD PSI is much different/higher than when it is 90 deg for the 1st track session. But the process of lowering the pressure after each session is the same.
Note: If you are running a 2-day event, you will need to "air-up" the morning of the second day since you will have let so much air OUT of you tires. I might find 2nd day starting PSI as low as 20 PSI before adding back in air.
Start out in the morning with factory "COLD" tire pressures (likely 35 psi), and then check them ASAP at the completion of each session when you pull back into the paddock. Then let the excess pressure out down to not more than 40 PSI "HOT"....do this after each session.
After you get a better feel for your tires/track/ambient Temps/etc, you will find that you use a COLD STARTING pressure of as low as 30-32 and different front-to-rear and left-to-right pressure differences as suggested below. Or you may find on a really cold day (new freezing) that you may need to have a higher pressure (higher than factory cold pressure recommendations) for the 1st session of the day. For example: I sometimes run LF= 30 psi, RF 32 psi, LR=31, RR=32 on a predominantly "right-turn" track since the LF tire will get hotter than the RF...same goes for the LR tire. It normally gets hotter than the RR, thus the tire pressure will grow at different rates so my starting psi is different, but reach a similar "hot" psi on the track.
I live in Atlanta, GA and we track all year long. So when it is 30 deg in the mornings, my COLD PSI is much different/higher than when it is 90 deg for the 1st track session. But the process of lowering the pressure after each session is the same.
Note: If you are running a 2-day event, you will need to "air-up" the morning of the second day since you will have let so much air OUT of you tires. I might find 2nd day starting PSI as low as 20 PSI before adding back in air.
01-13-2009, 11:52 AM
#696
A day late and a dollar short, but here are my 17x10 +25 FNs with 275/40 rubber.
akomsr1: It'll be close. It'll probably more depend on which tire you choose and if/when you change your suspension set-up. My +25s were so close to the upper arm that I ran a 3mm spacer; then they lightly scuffed on the outside edge. That puts them at a net +22, yours will be an additional 4mm out. You may need a lot of camber or a smaller tire to not scuff the outside. I'll probably try a few gentle laps without the spacer next time to grab some more room, as I've seen people run 275s with this set-up a bunch. The 275 Hoosier may be wider than another 275 tire you choose though:
akomsr1: It'll be close. It'll probably more depend on which tire you choose and if/when you change your suspension set-up. My +25s were so close to the upper arm that I ran a 3mm spacer; then they lightly scuffed on the outside edge. That puts them at a net +22, yours will be an additional 4mm out. You may need a lot of camber or a smaller tire to not scuff the outside. I'll probably try a few gentle laps without the spacer next time to grab some more room, as I've seen people run 275s with this set-up a bunch. The 275 Hoosier may be wider than another 275 tire you choose though:
01-13-2009, 01:08 PM
#697
Registered User
iTrader: (1)
Join Date: Dec 2006
Location: chicago
Posts: 106
Likes: 0
Received 0 Likes
on
0 Posts
Thanks Scott (and thanks for replying in my other thread too)
Although Hoosiers should run much wider than street tires in the same size, their specs show they have the same section width. Maybe I'll go with a 9.5 inch square setup just to be safe.
Although Hoosiers should run much wider than street tires in the same size, their specs show they have the same section width. Maybe I'll go with a 9.5 inch square setup just to be safe.
01-14-2009, 07:18 AM
#699
Registered User
iTrader: (1)
Join Date: Dec 2006
Location: chicago
Posts: 106
Likes: 0
Received 0 Likes
on
0 Posts
Scott, did you have any problems with the RPF1 17x9.5 +38 in front? Would this be a safer fit than the +18 offsets they offer? I'm not sure how much suspension clearance our cars have.
01-14-2009, 08:40 AM
#700
Depends on what tire brand you choose. The 275 Hoosiers are supposed to be run on a 10" or more wheel (even though I ran a set of R5s on 17x9.5s for years without issue). You'd need a spacer with the +38, but I think that may be a better choice than the 17x10+18 in the front with a 10 or 15mm spacer if there aren't other sizes available.