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Discussion Starter #1
Hey I am tracking my car this weekend at VIR and I was wondering what tire pressures I should run on my 195/60/14 falken azenis all around, I know what I run on my usual 205f/225r setup but dont know about 195's all around.

Thanks
Max
 

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I played w/ it until I got 32 hot all the way around, but I can't honestly remember what they were at cold...I want to say 26 psi up front and 24 in the rear...it was pretty low though.
 

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Before each session, make some marks (I usually do 3 each at about 120 degrees) on the tire with chalk/shoe polish that runs radially across the tread/sidewall transistion. After the session check how much of the marks wore off. If the wear is up the sidewall at all, add pressure. If it doesn't even reach the edge of the the tread area, reduce pressure.
 

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What does the "max" tire pressure on the side of the tire say?

And what DO you run on the other tires same brand?
 

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Discussion Starter #5
The "max" says 40, before I ran ~38 front and ~34-36 rear cold, but that was on toyo t1r's which are a different compound than the azenis.
 

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Well on a road racing circuit the worst thing you can do is not have enough pressure... sooo... I'd start out near that max pressure and check it when it comes in hot. If you're over say 50 hot I'd drop a couple pounds out and try again. (or if you can see tread distortion - and that's where Peter's trick will help a lot)

The 60 aspect ratio tires will want more pressure to hold solid.

There's obviously an optimum pressure which you could figure out with pyromoter but I don't think you're going for track records just for fun, so I'd err on the high side.

I can tell ya from experience with street tires - too low pressure and it's no fun at all sliding all over the place.

Also is it a MK1 or Mk2 or Mk3? At least on mk1 I'd personally run the same pressure front and rear... and maybe start with your 38 and see how it goes.
 

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Discussion Starter #7
Its a MkII and I usually start with a little more pressure in the front because it tends to oversteer a little, but now that I have so much less tire in the rear it might get real loose! That will be fun. :thumbup

But I think I will start them at 38 all around and see how it feels when were are at yellow all track and then adjust from there.

Thanks Thunderpaw
 

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makoff said:
Its a MkII and I usually start with a little more pressure in the front because it tends to oversteer a little, but now that I have so much less tire in the rear it might get real loose! That will be fun. :thumbup

But I think I will start them at 38 all around and see how it feels when were are at yellow all track and then adjust from there.

Thanks Thunderpaw

Stop by and say hi. I'm in the Red MR2, running in the green group #99.
 

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wow best of luck down there, hope it doesn't snow like it's supposed to up here.. now calling for two feet up here over the weekend.

In that case, tire pressure is pretty unimportant ;) good luck, have fun no matter what - bad conditions really teach you car control.
 

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makoff said:
Its a MkII and I usually start with a little more pressure in the front because it tends to oversteer a little, but now that I have so much less tire in the rear it might get real loose! That will be fun. :thumbup
um, thats why it oversteers, because the rears are lower than the front. Unlike some R compounds, with street tires, to get the rear end to stick more you'll want to add pressure there and reduce front.

Considering the weight bias, and relatively cold temps outside, I'd start around 32 front and 34 rear hoping to reach about 38~40 when hot.

Much more than that and the center of the tread will bow out and you'll end up with a squirrely car at high speed

have fun
 

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Discussion Starter #11
tommyg said:
um, thats why it oversteers, because the rears are lower than the front. Unlike some R compounds, with street tires, to get the rear end to stick more you'll want to add pressure there and reduce front.

Considering the weight bias, and relatively cold temps outside, I'd start around 32 front and 34 rear hoping to reach about 38~40 when hot.

Much more than that and the center of the tread will bow out and you'll end up with a squirrely car at high speed

have fun

I think you are mistaken the tire with the most pressure in it will break loose first, thus if the front has more air pressure it will loose traction first thus understeering. Thats why people buy stiffer front sway bars, because it puts more load on the front tires, creating understeer.

Anyways the event got called becuase of the nasty weather, but I still got to have a little drift session on the wet skidpad.
 

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Thunderpaw said:
Well on a road racing circuit the worst thing you can do is not have enough pressure... sooo... I'd start out near that max pressure and check it when it comes in hot.
This is generally good advice, but in an MR2 on Falken Azenis, I disagree. The main reason to increase pressure in a street tire is to reduce sidewall flex, since most street tires have soft sidewalls as compared to slicks or R-compounds. But Azenis have rather stiff sidewalls (ask any tire shop who's had to mount them :p ), and behave more like an R-compound with less grip than a true R-compound, rather than like a standard street tire.

Additionally, an MR2 is a very small car. While I ran 42 front / 38 rear with R-compounds on my Saturn SC2, I ran 32/30 on my Miata. With less car, you need less pressure to optimize the contact patch.

I haven't gotten my MR2 to a road course yet, so I can't suggest any pressure settings from my own experience.
 

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wow you guys run high pressure. I run 22f/28r cold. Any more I lose alot of grip. Gets to be around 26/32 hot.
This is on azenis rt-215 which has super stiff side walls. Even stiffer then some R compound dot tires imo.

This is on a mk3 tho which is alot lighter then mk2 or even a mk1.
 

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the front/rear pressure bias is consistent with what I had mentioned above, although your 'hot' pressures make me wonder that the tires are at truly at their optimum...despite the very light weight of the car.

I am unfamiliar with this tire, so I concede to your experience, but 'most' tires prefer the upper 30psi range for max grip. Throwing a very cold surface into the equasion throws everything right out the window however.

Re the understeer/oversteer issue above vis-a-vis tire pressure, pls click:
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=58

hope this clears it up for you :rolleyes:
 

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Discussion Starter #15
"Re the understeer/oversteer issue above vis-a-vis tire pressure, pls click:
http://www.tirerack.com/tires/tiret...e.jsp?techid=58

hope this clears it up for you "

I completely disagree with the top of that chart and your logic, some people who have more experience with tire setup and suspension will back me up, the tire with most force on it will break traction first for example a stiffer rear spring should create oversteer. I am not just making up some theory, I have a lot of track and autocross experience.
 

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You've got a number of things at work, the VERY bottom of the stack is understeer/oversteer.

You need enough pressure to keep the tire on the wheel when doing hard cornering -- a lot of factors go into this, tire construction, brand, aspect ratio, wheel width, suspension stiffness (stiffer suspension will require a higher tire pressure generally - in part because you'll be putting more G force on the tire), and how fast you're cornering. Too low pressure and the tire will rip itself right off the wheel.

Another aspect is tire deformation. Too high pressure and you'll lose some contact patch. However, in recent years it would take a LOT of pressure to cause this on most any street performance tire. But by too high you're talking WELL over the "max" pressure printed on the side.

Another aspect is higher pressure (ie denser) will increase temperature/pressure SLOWER than low pressure. This makes the tire more consistant. Ideal would be a magical tire that stayed exactly the same pressure no matter what. This is why one of the "tricks" many racers use Nitrogen to fill tires - it expands and heats slower and more consistant.

Heat - the other aspect. Too low pressure will allow the tire to heat up too much, and with tread will cause the rubber to melt too much. This will cause chunking (and sliding).

The only way to know the REAL optimal pressure for a tire is to go out and measure with pyrometer. For HPDE that's why I say just go with a nice high 30's and have fun.
 

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tommyg: The azenis is bit of a weird tire.

The RT-215 was I belive originally created as a enduro rain tire. So it has bit of a problem when you start running them on dry road. Mainly it heats up... ALOT. Thats why I run such a low pressure since theres no way to avoid adding 6psi after 2-3 laps unless I come in and water down the tires which isnt very practical. After 8-9 laps the tires do get greasy and lose quite a bit of traction. Makes a great autox tire since they have the best grip when stone cold.

Like Thunderpaw says run high 30s and have fun... this weekend? (NASA is having an event at VIR)
 

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Yep, thats what I guessed. I do recall an acquaintance having used them on a hot summer day (Golf) and having complained they went off very quickly...surprisingly, worse than most street tires.

makoff said:
I completely disagree with the top of that chart and your logic, some people who have more experience with tire setup and suspension will back me up, the tire with most force on it will break traction first for example a stiffer rear spring should create oversteer. I am not just making up some theory, I have a lot of track and autocross experience.
I have no doubt, but you're wrong in this instance and Tire Rack is correct (thats discounting my own experience since I started racing FF1600 in 1973).
If you don't believe Tire Rack, then click:
http://www.wtrscca.org/tech.htm this may explain that increasing tire pressure is not neccesarily the same as increasing spring rate.

hey, don't feel bad, I live and learn every day ;-)
 
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