Let's consider one more thing:

If your tires were manufactured in the 70's, please make sure that you have a good life insurance policy.

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When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

This is the same car that's in my signature 84 300SD.
The tires are Michelin Defenders 195/70R14.
The thing that isn't stock is that I put in the trailing arms, sway bar and
anti-squat hardware from a 500SEL in the rear end.

Jeff

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1984 300SD 300,000 miles--two tank WVO setup
2.88 diff & 500SEL anti-squat rear end

And here's the specs from the manual

Attached Thumbnails

 

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1984 300SD 300,000 miles--two tank WVO setup
2.88 diff & 500SEL anti-squat rear end

Tires made today are likely different than tires made 40 years ago, and what was printed in owner's manuals is well, a 40 year old technical marketing decision with other factors as well. I have made technical decisions and provided specifications for owner's documentation and I'll tell ya, I don't chisel it in stone or issue it via burning bush, and it's not entirely about best user experience anyways.

If people I trust somewhat have a good experience with handling and wear on a substantially similar car at 40 PSI that's enough for me to try it. I can always let it out.

My 300TD is definately loose in the rear on old and or soft tires, I'll put them at 40 just to see.

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CC: NSA

All things are burning, know this and be released.

82 Benz 240 D, Kuan Yin
12 Ford Escape 4wd

You're four times

It's hard to

more likely to

concentrate on

have an accident

two things

when you're on

at the same time.

a cell phone.

www.kiva.org It's not like there's anything wrong with feeling good, is there?

Almost as good as an oil thread!

Count me in the "higher is better" camp. I run the rear tires at maximum pressure (45 psi) and the fronts at 40 psi. Almost no wear after 30k+ miles.

I suspect that the worst trade-off is an increase in stopping distance, due to a smaller contact patch. Ride is also harder, maybe increased road noise on some surfaces. I will accept all of these in order to have longer tire life and improved fuel consumption.

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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

According to Tire rack, the Michelin Defender in 195/70R14 is rated at 1,356 lbs when inflated to 44 psi .

We need to determine what the brand, weight capacity and max inflation tires this car came with. Anyone have an original spare ? Also need front and rear GVW for the car .

Heavy truck and off road tires generally have a load vs pressure chart, I'm hoping to find one for the tires in question. The goal is to look at car corner weights and what a tire needs to be inflated to carry that load.

Tire inflation limits have been increasing over the years, the started at 32 then 35 and now 44 is common. If the original tires were rated at say 1,500 Lb at 35 PSI and a tire with a 1,500 Lb at 44 PSI rating is installed, tire pressure _must_ rise to carry the same load.

Have a look at this thermograph , I really with they listed actual tire size, rating and max inflation. Note how hot the bead area is due to tire flex . ( the bead is the ares just past the metal wheel )

Attached Files

Tire_Inflation_Matters_Car_and_Light_Truck.pdf (477.1 KB, 58 views)

I'll try higher pressures, why not.

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1998 Ford Escort ZX2 5 speed - 279,000 miles My Daily

1992 Mercedes 300D 2.5 202,000 - Pure junk
2000 Mercedes E320 Black - 136,000 miles - Needs repair

Don't forget to grease the screw and threads on the spring compressor.

This is a link to the truck inflation chart, still looking for a passenger tire chart. Note, the chart is for an axle load while the tire marking is for a single tire.

Also note that when dual tires are used, weight per tire is slightly reduced. Some of this is to take into account that a dual might be driving along a curb ( on one tire ), or uneven tire pressures cause one tire to carry more load than the other. When a dual tire fails, it is usually because the other dual is low on air causing the properly inflated tire to be overloaded.

https://www.michelintruck.com/reference-materials/manuals-bulletins-and-warranties/load-and-inflation-tables/#/

Truck tire thermograph https://www.michelinman.com/img/store/michelin_us/exit/pdf/Tire_Inflation_Matters_3_QTR_Ton_and_1_Ton_Trucks.pdf

When my 1 ton single wheel truck is driven unloaded / lightly loaded, I take the 80 PSI max to 35 F and 40 R and still have excess tire load capacity. Running pressure any higher than that is just too stiff of a ride.

Of course, when I load the truck with 6,750 LB of concrete pavers, pressure goes to 80 .

I have always understood that while higher tire pressures often mean a rougher ride that the higher pressure may contribute towards better fuel mileage.

Yep that is why the old Honda Insights were inflated to 60+ psi, and why they rode like train wheels...all about hitting the high fuel economy numbers to win them CAFE points.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

I had the original spare in my '84 Graymarket 300TD, it had never touched the road nor seen daylight and still had the paraffin coating .

I thought someone would want it for a show car or something but no one did .

If you notice tread center wear, you're running TOO MUCH pressure and your braking and road holding will be seriously diminished .

It's basic 7th grade physics guys, not rocket science .

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

I ended up using the original made in Germany spare that was 25 years while out of state and ended up forgetting about it. The tire lasted several thousand miles before coming apart in multiple pieces at low speed.

Dkr.

The various shops that work on our 240D keep setting the tires to 40psi, I keep lowering the pressure, but every time he goes near any shop it goes back up to 40psi.

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1981 240D Four on the floor, Orient Red over Parchment, bought with 154,000 but it's a daily driver and up to 180,000 miles, mostly original paint and all original interior.

I suspect the higher pressures are to protect the rims when running low profile tires that are so prevalent today.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.