Hoosier R6 Tire Pressure Advice Needed

[MikeW]

I got 205/45/16 and 225/45/17. I decided to stay with 225s for now.
These are R6 tires. I need a starting point for cold and especially HOT pressures. I have a pyrometer, but would like a ballpark number. Thanks

[lotusmark]

Hoosiers recommended pressures are too high. I start at 18 cold and try to get to 24 hot with a 15-20 degree difference across the face of the tire.

[Chris]

I agree with lotusmark, the lower psi the better. I assume this is because the Elise is a lighter car than others that might use this tire?

I was running max 25-28 lbs hot at the track last year. After a few laps, come in and make sure you are using the whole tire, if not keep lowering the psi till you are.

[MikeW]

I have a feeling I'll start high and come in and check the temps during a run and bleed off some. The car already has too much stuff in the trunk and no room for an air tank. Funny, I ran the A048s with 26 and 29 COLD. The temps came out nearly ideal.

[lotusmark]

Originally Posted by MikeW

I have a feeling I'll start high and come in and check the temps during a run and bleed off some. The car already has too much stuff in the trunk and no room for an air tank. Funny, I ran the A048s with 26 and 29 COLD. The temps came out nearly ideal.

Hi Mike

What did you consider ideal with the 048's?

[MikeW]

I was hoping no one would ask me that! I checked it on 2 occasions and can't find the data now. I'd say less than 20 degrees diference across, probably MUCH less. the car was lowered and aligned. Camber was 1.2 front, 2.6 rear. Temps showed that the car could still use 1/4 degree more camber. I was looking for someting to be wrong, I was darned close. The rear looked a little low temp wise in the center. We though there might have been something in the tire design that might have something to do with that. I called Yoko but they had nothing to support that theory.

[MikeW]

Just found it! Went to the garage and hoped it would be in my pyrometer memory. Found the sheet I wrote it on. Now I can't find the pyrometer!!!

Left ftont 29.9 psi Rt front 29.5 psi
151 154 149 139 158 166


Left rear 33 psi Rt rear 34 psi
156 151 174 178 162 170

the track I measured on had a bit more left turn activity,

You'll notice the rear center temps seem a bit low. Been running the same pressures all along now and rears are gone finally. Fronts confirm the need for just a bit more camber.

[AZReason]

Make sure you use the same pressure gauge to set your Hoosiers if you are setting them to the same pressure.

If I were you I would borrow someone's expensive guage at the track and compare it to what your gauge reads.

Looks like what my pyrometer readings when my rear 048's were heat cycled out. My readings showed too much camber in the rear, but new tires without a change in camber fixed that.

[MikeW]

Originally Posted by AZReason

Make sure you use the same pressure gauge to set your Hoosiers if you are setting them to the same pressure.

If I were you I would borrow someone's expensive guage at the track and compare it to what your gauge reads.

Looks like what my pyrometer readings when my rear 048's were heat cycled out. My readings showed too much camber in the rear, but new tires without a change in camber fixed that.

It's a good gauge, glycerin filled, can be equalized with atmospheric pressure.
Pryrometer is good too.

[robains]

Late on this thread, but it is interesting to me since I'm running Hoosiers now. I have a lot of experience with Hoosiers on a 3200 lbs race car, but none in my 1941 lbs Exige S. At BW I started 26/24, didn't get many laps (other issues) and had gone up to 28/25 but again not many laps, maybe 15 total. Due to other issues I wasn't able to put my tire gun on the Hoosiers.

As for your tire readings, assume you listed

Front OMI IMO
Rear OMI IMO

If that is the reference point then I suggest:
1. LF + 1 to 1.5 lbs.
2. RF either has too much or too little camber (pending IMO reference point)
3. LR + 1 lb
4. RR + 2 to 2.5 lbs

I'll be at Thunderhill (CA) this weekend and baring any major car issues, I'll have my support crew (aka wife) take some tire temp readings after 9-10 laps (come in hot before checkered session). I'm running the exact same Hoosier's you are and same size.

Where those temps A048's or the Hoosiers?

Would love to compare data with you.

Rob.

[fishguy]

Originally Posted by robains

As for your tire readings, assume you listed

Front OMI IMO
Rear OMI IMO

If that is the reference point then I suggest:
1. LF + 1 to 1.5 lbs.
2. RF either has too much or too little camber (pending IMO reference point)
3. LR + 1 lb
4. RR + 2 to 2.5 lbs

if i came off the track in the formula car here is what this info would direct me to do(after thinking about it).
assuming they were taken with a probe type pyrometer and the tires were still hot; and toe was (still) good(after the session as it was before the session):
1. (LF) looks fine(or close enough not to mess with it, you want ~ a 10% range across the tire with the pyrometer. this is what i was taught, and what i shoot for as my target as being acceptable).

2. add just a touch of negative camber, then after one session decide on air pressure. I find changing one variable at a time gives best results. i think just some more negative camber would do the trick, but make sure after setting the camber that your toe is still set correctly.

3. remove just a touch of negative camber, then possibly add 1/4-1/2 psi. but I would only make one change per session, and do the camber first

4.add 1/2 psi and adjust the psi the following session, camber looks fine to me.

doing more than one change per session is ok when you are really comfortable with the tools and the readings you get, and how the changes you make will affect things.
i used to see guys make "wholesale changes" in the pits when i raced bikes, and they never really knew what particular change did/didnt work when they went out next session.
when learning/testing, its best to only do one change at a time each session.

write down the weather conditions and other notes about the track(time of day for each run etc.) and save the set up on paper in your car note book that you always take with you to the track.
next track you go to you might make changes, so if its written down you can get close on the first session when you return to this track given other variables havent changed.

my additon of psi would be done while the tire is still hot, not when it cooled down.

then i would check my COLD psi before going out next session AND RECORD IT, and again check them hot when i come in AND RECORD IT before fine tuning if needed.

there are lots of approaches to things at the track. i figured i would post this so people could get different approaches to the readings given.
if you track the car and dont have a pyrometer..............buy one.
great tool to have, and buy the probe type, not the IR type.

[davecarama]

I had more experience with these in the Miata, but that said, if you are just starting out with them, why not start at the stock pressures? and check after each session?
Make half or one pound pressure adjustments at a time.
In the miata, I liked thirty something hot (was it 34, 36??? I can't remember even the stock numbers now)

So my vote is start at stock and adjust from there
26 front
28 rear

[chrisp993]

Disagree with Lotusmark - Hoosier have specific recommendations on their website for 1800-2200lb cars, see: https://www.hoosiertire.com/Tctips.htm

The default recommendation for 1800-2200lb car is 34-37lbs HOT. However, they also say:

Independent rear suspension
With IRS and proper geometry up front, tire pressures can be reduced from the recommendations listed above. When there is adequate camber gain and good roll control, the Hoosier radial tire will perform very well at the reduced air pressure. This results in a bigger "sweet spot" and easier control at the limit.

and

When tuning at reduced pressures use the following formula to determine the minimum safe pressure: Divide the total vehicle weight, including fuel and driver, by 100 to arrive at the minimum safe pressure. Example: Your car weighs 2750 lbs. as raced. The minimum safe (cold) pressure is 27.5 psi.

So, from this, minimum safe COLD pressure would be about 22psi and the Hooiser recommended pressure would be somehwere in the lower 30s

This matches well with what I've found to be the best HOT pressure to be in the 31/32psi range F/R. This needs a COLD pressure of about 23/24psi depending on the day etc. Experiment to find where in low 30s works for you. This HOT pressure gives me nice even temp gradient, 20F spread and perfectly even wear across the tire - note this is with fairly aggressive alignment of 1.75deg/2.8deg neg.camber F/R

Also, note the Hoosier website comment:

Higher pressures will improve the performance capability but will require a more sensitive feel to take advantage of the increase. One characteristic of the tires is the tendency to "skate" initially (when inflation pressures are correct). It is important to resist lowering the pressure to attempt to eliminate this feeling. Dropping the pressure too far may improve the "feel" of the tire however it will also lower the performance and increase the wear rate.

This matches my experience - I've run the Hoosiers at lower pressures e.g. mid to high 20s HOT and they feel a bit better initially, but don't grip as well. With the higher pressures they will "skate" for a couple of laps but work better IMHO.

YMMV

[davecarama]

Originally Posted by chrisp993

:

Sorry didn't want to quote the whole thing... just wanted to 100% agree with you. Best Hoosier tire post to date.

Start at stock pressures and adjust to where you are comfortable for hot pressures. Should be between 34 and 36 hot IMO. I bet stock pressures will put you close to 35 or 36 hot.

Dave

[DPM]

Fronts 22#

Rears 24#

Run this on both the Elise and the Diasio and get great wear and more importantly, they stick!

[dmh]

Originally Posted by MikeW

I got 205/45/16 and 225/45/17. I decided to stay with 225s for now.
These are R6 tires. I need a starting point for cold and especially HOT pressures. I have a pyrometer, but would like a ballpark number. Thanks

As a Hoosier dealer (Precision Motorsports Racing) here is what we have learned through championship winning years (through the compound changes – now 6) and installing hundreds and hundreds of them on our DE customer's cars...
If you…
are a novice to intermediate driver run the pressures on the low end.
are an experienced driver run the pressures on the high end.
want a feeling of confidence early in a session run the pressures on the low end.
want to go fast and have relatively no fall-off during a session run the pressures on the high end.

[robains]

So basically the answer is -- I'm gonna have to do my own testing to find out what works -- seems we have recommendations to run low and high and everything between.

So, I'll go middle of the road and start cold F 25 and R 27. One of these days I'll get real time IMO tire temp sensors like this and plug into my IQ3.

[DPM]

Don't use infrared probe, very inaccurate. Get a contact probe if you want ot do it right.

[robains]

Contact probe for real time data acquisition of tire temps?? Not sure I follow you?

The problem with using contact probes is the car has to be stationary and in the pits, the tires will cool too much and will not be representative of what the tire is actually doing on track. This IMHO is far less accurate that using real time infrared probes.

I agree that infrared sensors are not as accurate, but they are not so far off - and there benefit of real time data logging can show you the range of across the tire while driving on track -- the actual accuracy of the temp is not as meaningful as being able to monitor/log the relative change in temps across the tire during cornering.

The biggest challenge is mounting the sensors (at least for front).