Tire Pressures for a 930.

[Benny771]

Howdy:

Ive got a couple of friends with different opinions. One friend is a tire guy and the other is a Racer/mech (for years).
One said that the pressure should be near the max that is marked on the tire.
Other said follow the sticker on the car.
Which is right? They both had good points to justify there answers.

This is for street use.
What do you guys set at?

Thx. 1989 930

[Miguel Antonett]

It depends on many many factors, such as: wheel size, tire size, tire compound, suspension mods... at the end of the day w/o details I'd say 30~32 up front and 36~38 on the rear.

[mark houghton]

I run 32 up front and 42 in the rear with stock wheels and tires on my '87. Car sticker and the manual says 29 up front and 44 in the back, I think. From what I've heard, the 44 is more designed for extended high speed triple digit kind of stuff. Lower is most likely OK at "normal" speeds (but wait, "normal" for a 930 may not be below triple digits). Hmmmm.....I've confused myself again.

[Benny771]

For 30 in the front, what are the chances of a belt shifting? That is what my tire guy said to watch for.
I guess i could keep an eye on the temp's?

[Miguel Antonett]

What????? belt shifting????? Temps????? with 30#. Watch your tire guy...

[Noah930]

Originally Posted by mark houghton

Car sticker and the manual says 29 up front and 44 in the back, I think.

I go with that for my street-driven car. At the same time, I wonder if those ideal numbers might change as tire technology changes. As tire sidewall construction has improved and stiffened over the past 20-30 years, does that mean we can run lower tire pressures?

Additionally, if you change wheel or tire sizes, then you may need to adjust your tire pressures accordingly. If you're on the track, and you're going to be hard-core about it, then you'll adjust your tire pressures depending on what readings you're getting from your pyrometer and your handling preferences.

I would not go along with the "whatever's printed on the side of the tire" recommendation. That's ridiculous.

[WERK I]

Keep in mind tire pressures and suspension settings given by the factory were intended to give the 930's as much understeer possible at higher speeds. This would give the lesser experienced drivers warning that they approaching the cars limits and they should lift. A car with as much oversteer the 930 can have, this would spell disaster for the inexperienced.

Search the threads on Pelican for people who track or autocross their cars and want the most neutral handling they can find.

The factors are near limit-less......

[Noah930]

Originally Posted by WERK-I

Keep in mind tire pressures and suspension settings given by the factory were intended to give the 930's as much understeer possible at higher speeds. This would give the lesser experienced drivers warning that they approaching the cars limits and they should lift. A car with as much oversteer the 930 can have, this would spell disaster for the inexperienced.

Good point. If asked, I think most people feel the 911 oversteers. I disagree. I think that my car understeers quite a bit upon corner entry. Halfway through the turn, as you roll onto the throttle, the tail starts to come around.

[Miguel Antonett]

The understeer swaping to oversteer in a fraction of a sec is the greatest fun of driving our cars... NO electronics contol - YES!!

[e p slick]

Depends if you want tight or loose in corners. I personally like push/tight in the hills of Tucson.

EPS

NO-Bama country

[wcc]

Originally Posted by Miguel Antonett

It depends on many many factors, such as: wheel size, tire size, tire compound, suspension mods... at the end of the day w/o details I'd say 30~32 up front and 36~38 on the rear.

+1000000000000000......... Because this is EXACTLY what I do!

[jobah]

I autocrossed today and tried different pressures to get some thoughts on what works the best in my 930.

Based on recommendations from a couple of old 911/930 guys, I tried 29/44; 29/38; 27/34 and 27/32. The final setup was the best as far as traction and adhesion to the road.

I HATED 29/44 - felt like I had NO traction in the corners when things heated up. I actually spun out on a corner that I have been through dozens of times before - at a relatively slow speed.

Once I got below 29/38 everything fell into place. the final steup was the best, but 27/34 was also pretty good.

Btw, i'm running the sumi's on stock fuchs. It may be that as tire tech has changed, the original recommendations are no longer all that applicable.

[krasuskyp]

This is helpful Jobah, thanks for sharing. I assume you set / measured each setting cold (well, as cold as you can get them between autox runs)? Or are they purely hot settings? Just curious.

I wonder if these autox settings might work for a track event?

now

WHERE oh WHERE did you find an autox on a Thurs. afternoon? Kudos.

[zeb930]

For my Toyo R888s 295/30-18 and 235/40-18 on the track (hot)
Front 32
Rear 37

Steady and excellent grip for 15+ straight laps

[MT930]

There is thread in the track fourm on this. A lot depends on what you are running the car setup, weight few other factors. R compounds or street tires? track or street. Michelen Pilot Sport Cups have worked well for me 28 Front 30 Rear Cold they gain 4.5 Pounds warm with air. I have never tried nitrogen I understand heat will not change the pressure much.

[krasuskyp]

sorry - I meant to include those facts in my reply

same setup as Jobah - OE '87 bits, Fuzion ZR-i OE sized tires (meh).

tx

[jobah]

The set up was checked as cold as I could get it between runs. Most of the time, the car sat for at least 15-20 minutes. After the 29/44 setup. I checked the pressure hot, and it was over 50 in the rears.


krasuskyp - the autocross was at a track in Western Michigan. It was a private event and I had a buddy that was invited, and could bring along a friend. Of course, I jumped on it. I've been on that track before and the weather was supposed to be perfect.

[Noah930]

Originally Posted by krasuskyp

WHERE oh WHERE did you find an autox on a Thurs. afternoon? Kudos.

Heh heh. So that's what we're calling those midweek banzai runs through rush hour traffic, these days?

[JFairman]

This is a very interesting and useful thread accept most people posted their tire pressures without saying what size rims and tires they are using.

Big differences between the origonal 16" wheels or 17" or 18" rims and all the tire width, compound, and profile possiblities...

Seems to me without that information it makes it, kind of useless...

[Helios59]

Reviving this thread because of the all the possibilities.

I have a Turbo-Look with 205/55-16 in front and 245/45-16 in the rear. Street driven only.

I like 29 front/36 or 37 in the rear.