for those of you guys who run 205/50-16 tires, what's the correct or optimum tire pressure that y'all run at? thanks!

 

205/50-16 Kuhmos ..... I run 33 psi.

 

It depends on what you are looking for. For decent street handling and with a touch softer ride, 33psi sounds fine. For better lateral grip and steering response, but possibly a decrease in ride comfort (depends on tires and your own preferences), I'd start somewhere around 40psi front, 36psi rear.

Just so you know changing suspension setup, wheel width, and tire model can all drive slightly different numbers.

Scott
90SM

 

i have a new set of general exclaim uhp's. ride comfort isn't a big deal for me. i do want good handling and grip but also decent wear

 

35 for everyday [Kumho ASX]

 

I run the General UHP Exclaims 205/50/16 at 35 front, 33 rear. After experimentation with various pressures, this combination seems to work best.

 

thanks! doesn't get any more precise than that

 

How about you gals

No, seriously, what pressures on the track for 205/50/16? At the hpde I just attended, the group leader said that for the track, optimum pressure is close to the maximum rating indicated by the manufacturer on the sidewall. My GSD3's say 51 psi maximum so I put them up to 45. What do you guys (& gals) say?

 

With 45 psi I'm guessing your skidding and skipping all over the place. I've found about 33psi great in a set of 205/50 R16's. A good balance between handling and gas mileage.

 

33psi is fine for the street, but my question is what is optimum at the track? The group leader based his recommendation on maximizing contact patch under stresses encountered on the track.

 

I've used these on the track. I started somewhere near 36 then evened them all out to around 40, with a little more in the rear.

mb

 

I fill mine to 34 lbs.

 

Hohod,
on the track I will run 50+ on the fronts and 40 in the rear. The outside front will need more than the inside to keep it from rolling over in hard corners. Use chalk on the sidewalls of each tire and see how far the tire is rolling over when you come in to the pits. Adjust pressures accordingly.
I have 6 track days on my F1's and 30000 miles. Great tire.
For the track I just switched to Nitto NT-01's.
vince

 

Thanks vince - that's exactly the specifics and experience I'm hoping to learn from, so more questions for you: What other combinations did you try before settling on 50+/40? What did you like/dislike at each combo? Regarding the outside front needing more, doesn't this depend on whether you're cornering left or right? What tracks have you run? I've only been to Thunder Hill - 4 track days on oem runflats, 1 on GSD3's.

mbcoops, any reason you stopped at 40/40+? Thanks!

 

50+ psi

dang, i run that on my donuts.

 

Hohod,
I run at Thunderhill and Infenion. Last track day was with HOD Mini day at TH. I originally started by trying to get 40psi hot but the sidewall was to soft for that pressure and would roll all the way down the side. At TH with the big dowmhill at turn five and the force of the car weight on the L front tire it needed to have lots of pressure. I started with even pressure all around and got the sidewalls to just roll over to the arrow mark on the side wall. Then I experimented with lower rear pressures. Lower in the rear gave better grip and balance. This was with stock suspension. I recently upgraded to camberplates, TSW springs, H&R rear sway, stock shocks.
Hope this helps.
vince

 

Vince, that's great info. I misunderstood you earlier - I thought you were running one front higher than the other front. But you have both fronts at the same 50+ pressure because the LF needs it that high for turn 5 - correct? Was the rest of your car stock before recent upgrades? Mine is all stock with lsd. Thanks!

 

I've had the 15% pully since 2004. no other engine mods. Recently had the one ball done and changed to Alta air filter. I do run the outside front a little higher pressure than the inside about 3psi less. the only reason to go so high on the pressure is to keep it from rolling over to far. In theory as heat in the tire rises you would want to decrease pressure to keep the temp at the correct range for grip without blistering the tire. As these are street tires and not race tires they will slide more easily and and give you feedback with the noise.
At Infineon I can run slightly less pressure up front and more even since there is no flying through the air down hill landing hard corner
Will you be going to the HOD mini only day in Feb at TH?

 

Summer with F1"s 35psi
Winter 38psi

 

Why higher in winter?

 

Ideal Gas Law:

pV = nRT

Decrease the temperature, and either the pressure, the volume, or both decrease as well. If left at the summertime pressure of 35 psi, the colder temps will mean the fixed amount of air takes up less volume and the tires will be running a little flatter. So, adding back some volume by putting in a little more air results in the slightly higher pressure.

 

You've got the right principle in mind, but are a touch off on the details (though that might just be my interpretation of your description).

As temperature drops, pressure drops. True enough. To the tune of roughly 1psi for 10degF temperature change. That's why you should always be thoughtful about how you check/set tire pressures.

As ambient temperatures (or more accurately tire temperature) drops, more air molecules have to be added to the system to maintain a given pressure. The inverse also applies, which is why you'll see racers and autocrossers bleeding air out of the tire after runs to get the pressures back where they want them.

Not knowing exactly what minispeedrcr had in mind, I'll mention that I run my winter tire pressures a touch higher than my summer tires too. The sidewall construction of my snow tires is much softer than the summer tires (much less the R comps), and the mushy steering response drives me nuts at anything less than 40psi. Today we had a relative heatwave in Indy, so my pressures were 42psi in front when I was plugging one of the tires after running over a screw. I left them, as it will soon be colder again and the pressures will drop back where I intend them to be this time of year.

On a related note;

I believe manfacture specs are "cold" pressures, meaning that they are checked before you drive the car.

Road racers typically are referring to hot pressures, ie what they want them to be when warmed up on track. If you set your pressures in grid, they'll be several psi higher after a couple of laps. With exerience, you figure out where to set them cold so they are at the pressure you want hot.

If you go back and read my first post in this thread (very near the top), you'll see I've already commented that there is no single magic pressure that works for all tires models / sizes / wheel widths / suspension setup / tracks / driver tushes. I strongly suspect that that pressure suggestions in the 40-50psi range came from drivers who take their track time or autocrossing seriously and have some experience. Running somewhat lower pressures on the street will work fine for the vast majority of drivers, hence the MINI suggested pressures.

Scott
90SM