tires at 40 psi?
 

Just had an alignment done by a new neighbor at work who has
an auto repair shop. Not a MB specialist.
He inflated all the tires to 40 psi saying the tires would wear better
and that the original pressure recommendations don't apply to modern tires.

He also set the castor to 12* not 10*?

Anyone inflating their tires higher than what's originally recommended?


Jeff

I ran 40 on my 420sel. At 32 the outer edges wore faster.

Over inflating tires for improved wear, what kind of bull ***** is that? If anything over inflated tire give rise to increased center tire wear.

The original pressure doesn't apply to modern tires? What? Then he ignores suspension specs?

This man is a hack, STAY AWAY FROM HIM.
Edit:Maybe I'm too brash.

I run recommended pressure and haven't had any issues so far after nearly 10,000 miles

Sorry, but that guy is a moron

I do 40psi all around for road trips, 35 all around local driving. At the recommended tire pressure the outside edge of the tires wear out way too fast.

My 380sl has tire a reccoemndatoon of adding something like 10+ psi for "driving above 110mph". Something like 38 psi I think.

I like it because it makes the ride feel stiffer instead of soft.

Reminda me, I should check it again soon.

The newer models expect pressures in the 40s. My 2014 ML350 is like that.

Car has TPMS, and if it is more than 2-3 pounds below the specified value it starts making alarms.

most older cars were made when psi was not over 30,newer go to 50 psi on some. I run max for loads,and better wear,and higher mpgs.
some people are still stuck in stupid mode.

I ran factory spec for about the first year, crazy tire wear, dishrag handling. Alignment guy recommended highest possible pressures for tires so I upped to 41/44. I havent had any wear issues since (2 years), ride and handling are pretty good. He said the car was pretty heavy for the tires (General).

Two items to consider;

If your tires were manufactured in the 70s then maybe factory spec is OK, but I dont think the factory specs very much apply 50 years later for the reasons the factory chose those specs. Perhaps the relative front/rear balance is still applicable.

The reasons for the factory specs are unknown and may not apply to your use of the vehicle. We got a very small glimpse into how factory sets tire pressure specs with the ford exploder incident. In that case it had very little to do with performance or emergency handling, or longevity or... it was all about ride comfort/noise. Thier fix was to up the spec, no changes to the vehicle. Theres a lesson there, factory spec is aimed at things you may not care/want and for tires being manufactured at that time.

Not that I advocate changing things for no reason, but I wouldnt sweat upping pressures for performance/longevity reasons.

Proper Tire Pressures
 

Radial tires require higher pressures than Bias Ply do, many are still stuck in the past and are afraid to learn new things .

The manufacturer's pressure recommendations are always biased to a softer ride, always .

To learn the proper pressure for your particular vehicle, roads, load and driving habits, paint / chalk a stripe across the tread then drive your normal driving and see where the stripe wears off and adjust accordingly .

No one ever will reduce the pressure from the manufacturer's specification .

In general slightly higher pressure yields a firmer ride, better handling and longer, more even tire life .

We need more details.

Year , model , original tire size / current size , bias or radial ( original and now ) , recommended factory PSI , Front and rear GVW .

I usually stick pretty close to the recommended pressures. I used to put in more air because I liked the sharper feel of turning. Then when the tires started wearing out in the center of the tread I backed it off. Now I like a smoother ride.

This has also been my experience.

Sounds like BS. What tires are you running?