Tire temps

[ViperCr8zy]

I just took delivery of an '08 ACR, and I'm somewhat used to cars that take care of niggling things like traction control for you

I'm being very careful with the new beast until I fully understand its road manners. I've read a lot about tire temps needing to be up in order to not go sideways when hitting the throttle, but I've never seen a tire temp measurement listed. At the risk of being completely obsessive, what temp should the tires be at or above on the Sport Cups before I can feel comfortable pushing the car? I have an infrared thermometer tool, and want to be very sure I understand the correct temps before venturing out into the cool Northeast fall weather. Thanks!

 

[mjorgensen Woodhouse]

The inferred tool is useless for measuring tire temps. The surface is not what you need the temp of but down in the tread with a probe style pyrometer. The temps will start to give you the best grip at around 150 degrees and up to probably about 220. You need to measure at three points across the tire while they are still hot (right out in the hot pits done by another person), the temps equalize very rapidly so for a true read you need help. You will not see these on the street only on a track so even though the PS cups have more grip than most you should still be wary till they are warm.

 

[ACRBruce]

Optimum temp is between 160 to 220C. For more details, here's Michelin's Care and Feeding Instructions for the PSC.

http://www.tirerack.com/tires/tiretech/general/Michelin_Care_and_Feeding.pdf

 

[Grant]

My ACR gets full traction in 1st on most decent surfaces. When it does spin, it feels very stable (actually the most stable of any car I can remember driving!). This is in 55-80F weather, I'm sure its much worse when colder. Its going to be very hard to get the PSCs up to temp on the street.

Of course, if you aren't used to correcting for power-oversteer you should be cautious. Autocrosses and low-speed track events (such as are often held on karting tracks) are probably the best places to learn to deal with that sort of thing. You typically don't pick up much in the way of car control skills at HPDEs.

 

[tiger6]

Couple of thoughts. Agree that you will probably not get the tires on the ACR up to "optimal" grip temps on the street. On cool days with cool roads, cool tires, cool driver etc, be very careful going to power during or after a turn. This is where trouble can happen. If you can find an area such as a large vacant parking lot, you could play around with the car to see what it will do from a standing start and street level turns with power. If you take it to a track[road course], set the cold tire pressures to 25 psi front and 28 psi rear with 32 and 36 hot pressures as an objective. Spend LOTS of time in the slowest run group with an instructor while you learn more about the track and what the ACR will do with/to you as the driver. As has been said many times about this great car, she does NOT suffer fools gladly and will bite hard if not driven within certain limits.

 

[mopard150]

So driving in cold weather is possible, you just need to be carefull based on my reading here. Is there an outside temp that when arrives I should put the viper up for the winter. Right now the temp varies between low 40's and high 50's. I feel safe driving in 50 plus weather. Should I not be driving in 43 to 45 degree weather?

 

[fireball]

I've already driven mine in below zero temps. The tires never get enough heat to get good grip - but there's still a difference between cold and warm tires. I always leave from a heated garage so I'm not starting with frozen tires but it still makes a difference. As long as the roads are clear and your not going to drive like an idiot I say keep driving. It's just like having a few hundred more horsepower!

I drove at Sears Point 2 weeks ago on a very, very wet track and tire temps still came up enough that there was a very pronounced difference in grip. This on a flooded track! See thread http://forums.viperclub.org/srt10-srt10-coupe-discussions/620063-acr-dive-planes-extreme-use.html for some wild pics.

 

[mopard150]

Thank you. The pictures on the other post are awsome BTW. Still trying to get over the fear that a v10 520 horsepower car has when behind the wheel.

Day 12 of being a viper owner

 

[fireball]

Thank you. The pictures on the other post are awsome BTW. Still trying to get over the fear that a v10 520 horsepower car has when behind the wheel.

Day 12 of being a viper owner

It's a healthy fear. Don't get over it - it could cost ya.

Greg

 

[ulllose]

Thank you. The pictures on the other post are awsome BTW. Still trying to get over the fear that a v10 520 horsepower car has when behind the wheel.

Day 12 of being a viper owner

520???? What year car?

 

[mopard150]

Its a 2000 RT/10. Stock 450 HP. The car has some engine and exhuast modifcations and got me upto around 500 / 520 HP. I have not had it on a dyno for a while. Thats the goal next week to get an exact number. Should be fun to watch on the machine.

 

[Nader]

Mark am I reading this right? Did you buy a Viper? The Mamba that was posted on this site a while back?

The inferred tool is useless for measuring tire temps. The surface is not what you need the temp of but down in the tread with a probe style pyrometer. The temps will start to give you the best grip at around 150 degrees and up to probably about 220. You need to measure at three points across the tire while they are still hot (right out in the hot pits done by another person), the temps equalize very rapidly so for a true read you need help. You will not see these on the street only on a track so even though the PS cups have more grip than most you should still be wary till they are warm.

 

[fastlane8]

Optimum temp is between 160 to 220C.

320F to 428F are you F***king kidding???

 

[JonB]

I have used both the hand-held probe style (the best) and the hand-held infrared (OK, better than nothing) And the bare-hand method as well! (OUCH!) If you use the IR, be sure to be CLOSE to the tire, which can be difficult to get the inside shoulder reading. The actual 'tread' temp is about 10-20f HOTTER than the surface temp of an IR.

The key is measuring immediately after a HOT LAP, QUICK IN-LAP. NO COOL-DOWN, NO LOLLYGAG. Crewman must take temps right away...... a LOoooongg pit wall at 30mph pit speed lets the tires cool down a lot...especially the surface temps as IR measures. Take temps as CLOSE to the off-track exit as you can!

Cr8Zy, If you are obsessive / fanatical, for $175 you can get INTERNAL temp and pressure monitors as below that display the internal temps! Photo shown TOP is PRESSURES, but you can change display to TEMPS as LOWER PHOTO. Mind you, it tells the air temp inside the tire, not the tread temp....but its SOMETHING!

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Here are the displays Before a drive:

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[ulllose]

Its a 2000 RT/10. Stock 450 HP. The car has some engine and exhuast modifcations and got me upto around 500 / 520 HP. I have not had it on a dyno for a while. Thats the goal next week to get an exact number. Should be fun to watch on the machine.

Oh.......that makes sense, just sounded funny