I have Kumho 17" tires, and most tires I see have a wide range of pressures. Choices usually seem to run from 28-50 under max weight. What are pressures you all using, and why?

 

50! . If you're using 50 psi of tire pressure you're out of your mind. I run 31 in front and 33 in back on my tires (Yokohama Parada Spec-2's).

Depending on how hard you drive your tires will go up between 4 and 14 PSI as they heat up. On the track I start out at 32 PSI in the morning and by the end of my first run it's at 44-46 PSI.

Using the same logic, if you were at 50 PSI, by the time your tires heated up normally (first off you'd only have about 65% of the tire on the ground at that point because it'd have WAY too much air in it) you'd be closer to 55-60 PSI. Dangerously high (Blowout).

If you don't drive agressively, 34 front and 36 rear will work fine. If you like to have a bit of fun now and then, drop it down 2-3 PSI in the front and back...

 

I like 34 to 36. Hubby puts in 40 for autocrosses, but I think it feels squirrelly at that pressure; also hard riding. For sure, I go back to regular pressures as soon as we're done. Our autocrosses are short--under 1 minute per run. times 6 or 7 runs.

50?!

 

My all-season runflats are 33x4, my winter tires are 30 front 35 rear.

 

The door sticker on mine says 41 psi for speeds exceeding 100 mph, so that's what I run in my tires since I like going over 100 mph whenever the conditions allow it!

 

the Service Manager told me to keep it at 38psi. I have the Dunlop runflats.

 

Yes, I have noticed this as well. Why the higher pressure at higher speeds if the tire is going to heat up more? I filled mine up after break-in period, nonetheless.

Also, don't forget that as the weather gets warmer, the pressure will rise naturally a bit.

 

Yeah that's the main idea I think.The pressure does vary with the seasons.By several pounds.I've got the stock tires and I use 33 x 4.I make adjustments every 2 weeks, in the am, and without the sun heating up one side (I keep that one inthe garage but the others I get up before the sun heatsup one side)

 

When in doubt, just go by the manufacturer's recommended pressure that's on the driver's door jam. 9 times out of 10 it is what you need to run.

Do not go by the sidewall of the tire. I'd really like to know where people heard of this method. Does anybody know?

 

I run my Dunlop runflats at the door-jamb recommended 38psi.

The choice of tire pressure requires one to balance comfort vs. safety. I suspect that a tire with greater air pressure will generate less heat, so be safer at speed, but this margin of safety is needed only at those higher speeds. For typical speeds, the more comfortable lower pressure is satisfactory.

 

Canadian owners manual says 38 for the 17" runflats and that's what I run for normal driving.
What's printed on the sidewalls is the MAX cold pressure, not the recomended tire pressure.

 

Pirelli Eufori@ 205-45-17 run-flats at 35psi all around.

 

40 all around.

 

40 lbs all four runflats

 

The manual recommends 33 psi for the MC with any tire size from 175/65-15 to 205/40-18, unless you are driving over 100 mph with four people and luggage (I'm guessing this is for autobahn cruising). Then they recommend 36 lbs.

For the MCS, it recommends a variety of pressure settings that depend on the tire size, speed, and load.

195/55-16 is the same as the MC.

205/45-17 gets 36 psi for USA conditons, 41 psi autobahn/full load.

205/40-18 and 175/60-16 M+S take 38 psi. USA, 41 autobahn/full load.

All pressures to be measured with cold tires.

I'm running 205/45-17 Michelin Pilot Exhalto PE2 right now on my MCS. I checked the pressures before a trip up to San Carlos. It was colder than when I last measured them and either the temp or loss of air caused them to read around 34 to 35. So, compromising between the manual and the door sill, I put the fronts at 37.4 psi. Since I don't have much load on the rears I only ran them at 36.

The result was that, as expected, the ride was a little harsher. The surprise was that road noise levels at least doubled.

 

Funny--my door sticker says 38/38. Mine was ordered with a Sport Package (includes 17" tires), but through a dealer trade I got the 16" that I wanted. Guess my 34-36 (usually 36) makes sense.

 

OEM tires with 16" wheels are supposed to be 33 psi. You might check to see if yours are wearing faster in the center of the tread than the edges. If so, drop the pressure.

My door sticker also says 38 (Sports Package with 17x7 Crown Spokes).

 

Nope--just the opposite.

 

Interesting. Do you corner hard?

 

Autocrosses occasionally--maybe 5 a year x 45 seconds per run x 6 runs x 2 people. That's not too bad, I think. That's at 40 psi.

 

40 so when i go to autocross I can always let some out On my summer tires with good sidewalls ~35 seems optimal when hot for autocross.