Tire Pressures again!

[John Clarke]

Hi All
I have simply forgotten. The 356 (61 T5B Coupe) sits in the garage long term, so the tires are down to 15 psi !
After running Michelin XZX for many years, we are now on a new set of Vredestein Classic Sprint Tires. They are 165 x 15 on 5 1/2" EMPI 5 spoke 205 Alloys. Everyone seems to have their different favourite pressure combination. We run approx 2 * Negative camber at the rear. I have initially put 26 psi in the Fronts and 32 in the Rears.
What are Your thoughts? All just part of getting the car back on the road for this Years Classic Le Mans in France in July, So the car will be loaded up with all the camping gear etc.
Many thanks in advance for any replies.
Kind regards Jay

[Doug McDonnell]

As you say everyone has their own thoughts. Your pressures are fine for running the twisties. Maybe drop a few pounds for more comfortable touring. Personal preferences. https://porsche356registry.org/article/210 And here is another recent discussion: viewtopic.php?f=1&t=43368&start=15

[Dick Weiss]

Rear camber @ 2-degrees negative is excessive and adding luggage for a road trip really may cause problems.
Also, running skinny 165 tires on wide rims can effect handling--the same situation w/wide tires on skinny rims.
My $0.05 worth. (todays economy)

Dick

[David Jones]

John, put an extra 3 to 5 pounds of pressure in the rears with the heavy load aboard and that will compensate a little for the extra camber and crown out the tires a little to reduce wear on the inside of the tire. Just do not try any hard cornering until unloaded and you go back to normal pressures.

[John Clarke]

Thanks Doug
Dick, The 165 is the Minimum width tire listed that you can run on a 5.5" rim. The 165 Vredestein Sprints don't look 'undersized' on the EMPI Alloys and the Negative camber has never seemed excessive. Does look good though!
David, thanks , I have the rears at 32psi and would have thought an extra 5 psi (37psi) would be a little high. But this is what I'm asking. Thanks for your help.
Jay

[David Jones]

John, I am not saying you should run as much as 5 psi more but to try running up to 5 psi more pressure though as you are running 32 I have to reduce that 5 to 3. Radials do put more tread on the ground than cross/bias ply tires because the side wall is more flexible so it is harder to "crown" out the tire but at speed centrifugal force lifts the tread away from the tire walls and a little more pressure will help in that regard thereby reducing the temperature build up on the tread. Load the car up and drive it. It will tell you if it likes the higher pressure. I bought some Nexen tires for my "A" coupe and it hates them on the rear, very squirrely. Sidewall is way too flexible even up to 45 psi but they work on the front at 25 psi. Full disclosure, they were OK driving sedately at 30 psi on the rear but I have been known to not drive sedately.

[Dick Weiss]

OK John,

It's your preference; Not mine.

Dick

[Thomas Sottile]

If you were going to race at La Mans this would all be important, but a few lbs. one way or the other, give me a brake!! don't forgot to check the altitude, temp, and wind in your calculation

[John Clarke]

Thomas
On the registry site, we have to be polite and play nice. They are the rules!
Our cars as I'm sure you know Are affected much more with tire pressures than a lot of others. If I thought it would help, I would gladly supply you with altitude, temperature & wind speeds & ask you to do the math !
I don't need sarcasm, just some helpful answers which we normally receive here. If you haven't got anything positive to add, Don't post!
Thanks Jay

[Emil Wojcik]

Actually, most here, including me, will tell you a few pounds one way or the other can make a very noticeable difference in spirited street driving.

Personally, I've found 30 lbs in the rear allows me to get out of my driveway without scraping, and four pounds less (26 lbs) up front gives the best handling for the way I drive. It's the four pound difference that I find more important than what actual pressures I use, within reason of course.

[Martin Benade]

Emil's idea is reasonable. And 2 degrees negative camber never did anything very drastic to my tires, but I have only 40 years of data so far. I am still studying it.

[Thomas Sottile]

Take it easy John, I was just kidding. I should have put a Smiley up there.