Wow, this is the most cost effective upgrade ever made on a 911
 

sorry for the dramatics, but here it is. yes i'm still a newbie. i got my 86 911 targa alittle over a monthe ago. i have changed the oil, adjusted the valves, changed the trans oil , changed to a whisper coupler, added a chip etc.....but i finally got around to checking the psi on my tires.......they require 40 psi in front and 45 in rear. i'm embarressed to say they had 20 psi. added it tonite, and what a difference. everything runs better now. almost everythingSmileWavy

"like"

This is what it says on my tire inflation sticker in the engine compartment of my 86' coupe. It's a good starting point with minor adjustments for personal taste. There are plenty of threads on tire pressure variables.

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What kind of tires........
 

rinverso,

What size and type of rubber tires do you got that have to be inflated 40/45 psi (F/R)? Are you using stock size tires? Keep us posted.

Tony

i didn't research too far, i just read the max pressure rating on the tires. they are z rated tires and say 50psi max front, 54psi max rear. they are 16 inch 225/50 rear...205/55 front i beleive. what do you think?

Get a tire pressure sticker so you know what to set your tires to:

http://forums.pelicanparts.com/porsche-911-used-parts-sale-wanted/572976-tire-pressure-decal-1978-83-a.html

You should inflate the tires to the specs printed in the owner's manual or doorjamb sticker (29/36). It won't be 40/45. Even on turbos it's only 29/45. You're not supposed to look at the tire max inflation pressure stamped on the tire sidewall; how is the tire manufacturer supposed to know what car on which you'll be using their tires? It'll be harder to beat the bang-for-the-buck return on proper air pressure settings.

From a performance perspective, the $60 or so your local PCA chapter will run for an autocross is also a pretty good performance upgrade. Plus what you learn will apply to pretty much every vehicle you drive.

ok sounds like i need to drop a few pounds, my wife said the same thing. i'll adjust the pressure to taste as suggested. going to do it right now actually. 29/36. better than 20/20 or 40/45

WAY HIGH!. Sticker will set you free.

BEST!

Doyle

wait till you re-fresh the suspension bushings :D

total different car

on street tires you can run them a little high. O have heard a lot of opinions but what it boils down to is rollover and wear - if your tires are wearing well and not rolling over, the presure is right - on track (have to get my log book but IIRC) I think I was running street tires about 46 all the way around HOT

now with it being cold you might want a little less (snow likes slightly less inflation) - and in summer watch for growing pressure on long trips - they can easily gain a few pounds when warm - at the track i can gain 6-8 psi on street tires

as the tires wear watch the inside edges of the rears - unless you drive the car (and I mean actually drive fairly aggressively) your innner edges will wear first - get on your hands and knees and look at them - OFTEN - they wear fast!

a little lower pressure will get the wear back to center more and turning with some speed will do the same thing - rotating tires (flipping on the rim) is a great way to nearly double the life of a set of tires

lastly - get a good gage - like this - it's worth it - really!
Longacre Tire Gauge Glow in Dark 0-60 psi : Amazon.com : Automotive

I run the same size tires and 32 front/36 rear seems to be a good setting for ride, handling and tire wear.

I should add: yes 32 /36 is a good place to start on the street - my above reference was perspective as to the range and use of different tire pressures for different situations

but I am 32/36 on street

+1 That's my summer range.

Baby, when it's cold outside... I drop it to 29/34 and it's basically to go out on sunny winter days when temps get into the 40's. Not really pushing, just getting temps up and things circulating.

i do the chalk test. draw a line across the tread with chalk and roll the car forward til you go over the line. you can see what you need to do at that point - chalk worn off in the center? over filled. edges? under filled. repeat as necessary until the chalk line wears evenly.

They don't require 40 psi and 45 psi. that's way too high.

Relays for the lights and the replacement steering bushing.

45 in the rear would make for fun over-steer experiences in these cars! Just be ready when the tail starts coming around.

It could be argued that tire pressure at the basic level is maintenance. Adding an air freshener is an "upgrade"

I can't imagine what the ride must be like at 45 lbs per. My '84 will beat me half to death at 39 in the rears. I try to keep the pressures at 33 front and 36 rear and even that can be harsh over some surfaces. :eek:

If I may suggest, get a $25 pump from pepboys and a decent gauge and go 29/36 oem spec for optimal street use, if tracked lower it about 4 - 6 lbs and adjust for your needs.

J