Tire Pressure ?

[Knome_#2]

Hey All, I just purchased a set of Kuhmo Exta XC's in the standard size for a 97. I ran them for a week and checked the pressure this morning and found them at 36.5 front and 35 rear. My first thought was they set them way high to get a good bead set on the wheels while new. But as I have never bought Kuhmo's before I thought that maybe these just require a higher pressure. Does anyone know what the normal pressure for these tires are for street work?
Thanks

 

[nsxtasy]

What's a "Kuhmo Exta XC"? You wouldn't by any chance be referring to the new extreme performance tire, the Kumho (not Kuhmo) Ecsta (not Exta) XS (not XC), would you? :smile:

I would start out at the Acura recommended pressures of 33 psi front, 40 psi rear. These numbers are "cold" measurements, i.e. measured at about the same temperature as the car will be used, with the car sitting indoors or in the shade, not having been driven in several hours. See how you like them. If you're not happy with the results (in terms of ride comfort, handling, and/or even treadwear), you could then adjust them as needed by adding or reducing pressures in 2 psi increments, front and/or rear. (FWIW I've been very happy with 33F/40R, even when using my 16"/17" wheels with '94-01 stock sized tires.)

 

[slamstrom]

Listen to Ken. He is Prime's Tire guru.

 

[Big_D]

I agree with Ken... 33 PSI Front 40 PSI rear.

 

[FXMDBilly]

I respectfully disagree and do not wish to debate or argue my point further than to simply state that for anything with a 215/255 or 215/265 or 215/275 or 235/265 etc... I recommend and run 36psi cold on all four corners.

I do not like the stock Honda recommendation of 33/40psi Cold for anything other than the tiny 205/225 tire sizes.

Most street tires generate the most grip at 36-38psi hot. Since the NSX has staggered tire sizes, having all 4 tires at their optimum will give the NSX more grip in the rear due to the stagger. On a racetrack you set your 'cold' tire pressures much lower to have the heat and pressure build up to this ideal tire pressure. If you set your pressures at 40psi cold, they will go well above the ideal grip level, reduce the contact patch, and reduce rear grip.

For the street, you don't get the heat or pressure buildup that you do on the track so running 40psi cold is probably fine. But this cold pressure is still above the optimum hot pressure/grip. Because of this I tend to run 35/35, or if I go on a long trip i do 40/40 for better gas mileage while keeping the balance of the car (I dont reccomend it).


0.02 -Billy

 

[robbiedawg]

billy, thanks for your always helpful comments.is your rec of 36 psi all around just for the track? if it is,what do you rec for a car that's not tracked,just driven quickly on the street?

 

[FXMDBilly]

billy, thanks for your always helpful comments.is your rec of 36 psi all around just for the track? if it is,what do you rec for a car that's not tracked,just driven quickly on the street?

I set my NSX at 36psi all around on the street. If i'm driving to Vegas or 5+hrs to northern california and want 1-2mpg better, I might bump it up to 40psi all around and while the car will react slightly quicker due to the higher pressures, it will have less grip.

For the track, a good rule of thumb is for every 10*F ambient air temperature, tires will increase 1psi. Ex): on a 80*F day, tires will grow 8psi.

On an 80*F day, if I want 38psi hot, I will set the tires at 30psi cold all around.

I do this because I want to maximize all 4 of the tire's grip and then play with suspension or tire pressures to dial the car from there. Setting the fronts at 33 and rears at 40 could lead to an oversteering car when the pressures increase on track. For the street they are probably fine, but I still set my car at 36psi all around on the street. The front tires will feel more responsive than at 33psi.


Billy

 

[nsxtasy]

For best results, I recommend 33 psi front and 40 psi rear as a starting point for street tires. So does Honda and its engineers who designed, tested, and built our cars. I've used the 33F/40R pressure, measured cold, with street tires on the street, and also with street tires on the track, and in both cases I've been very happy with the neutral handling that results. This is a starting point; if you don't like the results you get, you can adjust it as needed. But I've found that Honda knew what they were doing when they developed their pressure recommendations.

R compound track tires used on the track are generally a different story. There is usually a "sweet spot" of temperature measured hot, one that is often stated by the tire manufacturer. With many tires it's in the 38-42 psi range, but consult your tire manufacturer's recommendations to be sure.