Recommended tire pressure.

[zippy_gg]

For those running Conti 205/55-16 and 225/50-16 on stock rims for street use, what pressure are you running?
The sticker on my car show inflation for 15 inch rims; also as tire technology has evolved quite a bit since 1986 I am looking for real life values and not sticker or tire manufacturer recommendations.
The car is stock 1986 cab.
Thanks!

[gtc]

Sticker on my car says 29/36 PSI. I run my tires at 32/39. YMMV.

[livetopedal]

I have conti extreme contact d/w in those sizes and run recommended psi: 29/36
Cheers!

[kanadary]

After I got my car lowered to euro height, the shop told me to run 34/40.

[macssc911]

Well if your taking your girl out for a comfort drive go with factory spec, now if your going to drive it like you are stealing it add 5 to 7 to each tire
Be safe

[azhodge]

Love this discussion. like to hear other opinions. I always thought the factory numbers were not optimal.

[Quicksilver]

There is no "correct" tire pressure. Different tires, uses, conditions, and preferences all work out to different tire pressures.

A conventional tire wants a higher pressure. Most slick or minimal tread R tires want a low pressure. For aquaplaning resistance in rain you want a higher pressure and for a comfortable ride you want lower pressures. (And why the hell did everyone go to tires with damn near zero sidewall on passenger cars?!!!)

The only way to optimize pressures for your use is to test them on a skidpad or some other constant radius turn where you have a controlled situation that allows you to safely push the tires to their limit to see which end of the car is working.

If you don't need that much then just use what is on the door. (For 16x6 and 7s that is 29/36.) For rainy weather you can just pump them up to the maximum on the sidewall.

[86 911 Targa]

For our '86 with 7's & 8's 205's & 225's,
I pump up the tires to 35F & 40R,
let sit overnight,
then bleed them down to 29F & 36R.

Good/even tire wear.

Best,

Gerry

[scarceller]

I have a 84 factory widebody and it came from the factory with 7" front 8" rear and those exact tire sizes 205/55/16 front 225/50/16 rear.
The sticker on my car says 29PSI front 36PSI rear.

So that's another factory data point from a widebody factory car.

I run 30PSI front 35PSI rear, handles well on the street.
Running Bridgestone RE760 street tires.

[zippy_gg]

Originally Posted by scarceller

I have a 84 factory widebody and it came from the factory with 7" front 8" rear and those exact tire sizes 205/55/16 front 225/50/16 rear.
The sticker on my car says 29PSI rear 26PSI front.

So that's another factory data point from a widebody factory car.

I run 30PSI rear 35PSI front, handles well on the street.
Running Bridgestone RE760 street tires.

Sal, am I reading correctly that you run much higher pressure on the front than the rear?

[Otter74]

I typically set mine at or slightly above the recommended pressures (205/55 and 225/50 Conti DWS), but what I am puzzled by is the people here who are running significantly *lower* rear pressures. This on a car with a significant rear weight bias.

[86 911 Targa]

Originally Posted by Otter74

I typically set mine at or slightly above the recommended pressures (205/55 and 225/50 Conti DWS), but what I am puzzled by is the people here who are running significantly *lower* rear pressures. This on a car with a significant rear weight bias.

For those who desire a softer ride, I suspect that lower tire pressures helps.

But, what about even rear tire wear?

Gerry

[zippy_gg]

Originally Posted by Otter74

I typically set mine at or slightly above the recommended pressures (205/55 and 225/50 Conti DWS), but what I am puzzled by is the people here who are running significantly *lower* rear pressures. This on a car with a significant rear weight bias.

These are the tires I am using.
BTW I replaced the worn out shocks with all around Bilstein Heavy Duty and did not change the torsion bars. All bushings were also replaced. So I am not looking for very high performance although I enjoy spirited drives just as I do on my Beemer.
Thanks!

[scarceller]

Sorry my mistake,

Factory spec for my car is 29front 36rear I fixed the prior post.

But I run 30front 35rear.

Originally Posted by zippy_gg

Sal, am I reading correctly that you run much higher pressure on the front than the rear?

[Quicksilver]

Originally Posted by scarceller

. . .

But I run 35front 30rear, so yes higher pressure in the front tires than the rear is the norm for most auto specs.

Those tire pressures are about the most dangerous thing I have seen posted here!

The "norm for most auto specs" are for cars that have about 60% of the weight in the front because almost every car made is front engined. The front pressure isn't dangerous, it is just unbalanced compared to almost any acceptable rear pressure. If I had arm or shoulder issues I might run elevated pressures in the front to reduce steering effort.

The reduced rear pressure is just plain dangerous. It will cause excess heating of the tire from the increased quantity of flex. (mostly in the sidewall and shoulder where it is most dangerous!)

60% of the weight of a 911 is on the rear wheels plus the rear wheels need to deal with the constant torque of propelling the car. A 911 is one of the best engineered cars in the world and deciding that you will "re-engineer" the critical tire pressures based on the fact that completely dissimilar vehicles have different settings is either arrogant or insane.

This advice can KILL someone. Period.

[scarceller]

Thanks for catching my mistake, I have that backwards I run 30 front 35 rear, sorry about the confusion. I fixed the prior posts.
And to be clear the factory sticker says 29front 36rear.

Originally Posted by Quicksilver

Those tire pressures are about the most dangerous thing I have seen posted here!

The "norm for most auto specs" are for cars that have about 60% of the weight in the front because almost every car made is front engined. The front pressure isn't dangerous, it is just unbalanced compared to almost any acceptable rear pressure. If I had arm or shoulder issues I might run elevated pressures in the front to reduce steering effort.

The reduced rear pressure is just plain dangerous. It will cause excess heating of the tire from the increased quantity of flex. (mostly in the sidewall and shoulder where it is most dangerous!)

60% of the weight of a 911 is on the rear wheels plus the rear wheels need to deal with the constant torque of propelling the car. A 911 is one of the best engineered cars in the world and deciding that you will "re-engineer" the critical tire pressures based on the fact that completely dissimilar vehicles have different settings is either arrogant or insane.

This advice can KILL someone. Period.

[Quicksilver]

Originally Posted by scarceller

Thanks for catching my mistake, I have that backwards I run 30 front 35 rear, sorry about the confusion. I fixed the prior posts.
And to be clear the factory sticker says 29front 36rear.

Wholy crapparino! You had me scared for your safety. Glad to see it!!

[IROC]

I was at a PCA tech session years ago where a Yokohama representative talked about this very subject. His response was to use the factory recommended tire pressures unless you have modified the car substantially or are using tires significantly different that what came stock.

My car came with 185/70-15s front and rear. I now have 225/45 and 255/40-17s on it. I still use the factory recommended tire pressures and they work just fine.

[hcoles]

for AX (not often these days) I run 35 rear, 33 front. I'm on stock wheels/tire sizes. 205 on 6?" fr and 225 on 8" rear all by 16" dia. I don't change for the street so that's what I end up running on the street also. Tires are wearing even as much as I can tell.

[bpu699]

Why such a high pressure in the rear? These cars are tail happy, and I would think lower rear pressures give a larger contact patch?

I run 35/35 on the track, before the even starts.... I am sure its much higher after....