Stock tire pressure - anyone follow it?

[Truemyth]

Hi, all.

Anyone follow the tire pressure as written on the driver door? 35 psi front and 33 rear. Seems odd that there's an offset.

Dealer filled it up to 35 all around but i'd like to know the long term effects from those that's owned a Type S for a while.

For those that does follow it, any thing notable? I doubt 2 psi might do much but you never know, could cause uneven wear perhaps.

Apologies if someone answered this or started a thread about this already as my forum search skill sucks.

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[RMA]

I always have mine 39 front and 36 rear.

 

[SilverRocket]

I always have mine 39 front and 36 rear.

I see I have a fellow connoisseur of manual page 660. I run 40/34psi.

As for the difference, the rear is most of the time just along for the ride, with a bit of braking. The front is handling the turning and acceleration too so it needs more pressure. I'd be willing to bet the offset tire pressure makes the wear even.

 

[elh0102]

Optimum tire pressure will vary substantially depending on the tire and the specific use. It's a safe rule that front drivers will fare better with more pressure in front. In hard driving, as on track, you just have to experiment to see where the best handling balance and grip is obtained. When front grip goes away, the car will tend to push straight through the turn. For general street use, any of the ranges mentioned should be fine, and most drivers will feel no difference.

 

[optronix]

It's offset to reduce the opportunity for oversteer. I typically leave it 35 all around because I'm lazy, but for autocross I want the car to rotate so I'm usually at least a couple psi higher in the rear. I don't think I've landed on any "magic numbers" yet and I'm usually fiddling with tire pressures in the grid but I think somewhere around 38/42 hot temps is where I'm at now, but that's only because of the added camber. Stock camber I filled the tires until they nearly popped; I was in the 50s in the rear IIRC.

For the street it really doesn't matter. 33-35 should be fine. I don't quite understand why you'd want the higher pressure for regular ass driving but to each their own.

 

[Frenzal]

I do try to follow it...

 

[StingertimeNC]

I like a couple pounds higher than necessary for my regular ass driving. LOL.

I always thought it helped with tire wear when you were running a bit too much camber because of being dropped on springs.

 

[Truemyth]

I see I have a fellow connoisseur of manual page 660. I run 40/34psi.

As for the difference, the rear is most of the time just along for the ride, with a bit of braking. The front is handling the turning and acceleration too so it needs more pressure. I'd be willing to bet the offset tire pressure makes the wear even.

It's weird that the door says one thing and the manual says another.

Thanks y'all for your inputs and thoughts.

 

[elh0102]

It's weird that the door says one thing and the manual says another.

Thanks y'all for your inputs and thoughts.

The higher pressures recommended in the manual are for sustained speeds of over 130 mph. Although your best pressures on track use will depend on your own testing, it will be higher than recommended for general street use. Tires get very hot at high speeds, and pressures build rapidly. Most of the track cars I had usually worked well at around 38 psi, but I was constantly bleeding pressure on summer days. 38 psi at track temps would be mid 20's by morning at the motel, so you're starting the process again every day.

 

[boosted_canoe]

I like a couple pounds higher than necessary for my regular ass driving. LOL.

I always thought it helped with tire wear when you were running a bit too much camber because of being dropped on springs.

i usually run a couple pounds less because that number is for a fully-loaded car. helps with traction and a smoother ride.

 

[elh0102]

It's offset to reduce the opportunity for oversteer. I typically leave it 35 all around because I'm lazy, but for autocross I want the car to rotate so I'm usually at least a couple psi higher in the rear. I don't think I've landed on any "magic numbers" yet and I'm usually fiddling with tire pressures in the grid but I think somewhere around 38/42 hot temps is where I'm at now, but that's only because of the added camber. Stock camber I filled the tires until they nearly popped; I was in the 50s in the rear IIRC.

For the street it really doesn't matter. 33-35 should be fine. I don't quite understand why you'd want the higher pressure for regular ass driving but to each their own.

I checked the pressures yesterday and set all 4 at 35 (previously 38/35). There are a couple of close highway interchanges where I can safely push the car at reasonable speed. These are low-speed turns, and 60 mph is probably 80%+ of the car's capability. I can tell no appreciable difference in handling. The front felt a bit softer, but if anything, grip seemed better, which I wasn't expecting. During this process, the tires heated up to about 38 psi. The car is totally stock. Granted, not a scientific test, and higher speed track conditions may have produced different results.

 

[StingertimeNC]

Heat/track definitely produces different results. At the track, on Conti Extreme contact 02's, 275/30 19's, good temp is 46-47 psi front and 40-42 psi rear. At least for me at VIR. The front tires roll over on the sidewall with lower pressure. It also seems to stabilize the rear under heavy braking.

I think I'll be switching to 18's with 200 TW tires before my next trip. Keep the 19's for daily.

 

[elh0102]

Heat/track definitely produces different results. At the track, on Conti Extreme contact 02's, 275/30 19's, good temp is 46-47 psi front and 40-42 psi rear. At least for me at VIR. The front tires roll over on the sidewall with lower pressure. It also seems to stabilize the rear under heavy braking.

I think I'll be switching to 18's with 200 TW tires before my next trip. Keep the 19's for daily.

Cars, tires, and suspension setups are all different. When I was doing track stuff with RWD cars, I would have lost considerable front grip at those pressures. But I agree that the weight up front here should require more pressure there. That said, I am a bit surprised that it takes that much pressure to limit sidewall flex to an acceptable level. But I have no experience with that tire.

 

[Cliffpc]

I start with 33 psi cold, about 10 degrees Celsius outside. After driving home from work I am at 38/37. 25 C outside.

I have seen 5 psi increase from just parking in the sun.

Moral is just keep an eye on it and be prepared to bleed or add air as conditions and usage changes

 

[elh0102]

For normal.street use, I would just put them within your normal range and forget about it. In routine street use, you will not notice the difference caused by ambient temp change or driving. A seasonal adjustment from summer to winter temps is normal, but otherwise I don't believe there is any benefit in micro-managing it.

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