Has anyone seen the number for max tire pressure on the tire's sidewall?
Looks like the number is 40 psi, but the car's placard would tell you to inflate to min 41, and max 48 psi.

 

I would use the manufactures suggested tire pressure. Not all cars weight the same.

 

I agree with the general principle, but when the pressure recommended by MB exceeds the max stated by the tire manufacturer, should we be concerned?
Say the tire blows up, the tire manufacturer will have no warranty or liability because the tire is not used "properly."

 

What make/model tires do you have, and what's the load rating? 40 psi max pressure is very low. I don't think I've ever seen that for an XL tire. The max pressure on XL tires is usually 50 or 51 psi. As far as recommended tire pressure goes, most cars usually have at least two. The one on the door sticker is the maximum load tire pressure only to really be used if you load up the car to its gross weight. MB puts a more detailed sticker inside the fuel door on ICE cars, I'm guessing its inside of the charging door in case of the EQS. It lists the normal load recommended pressure which is lower to account for the lower weight of a lightly loaded car.

 

​​​​​​Are not you confusing with a long story about setting the beads when mounting the tire., wich may not be to high fi 40 psi max.

Most personscartires have maximum allowed cold pressure of between 44 and 51psi, and an occacional XL 60 psi.

The reference-pressure for a standard load is 35 or 36 psi, and XL 41 or 42psi.

​​​​​For the reference - pressure and - speed the maxload is given
Q to V speedcode reference speed is 160kmph/99mph and for higher speed there is a system for highening up the refpres depending on speedcode in the official system.

Once read that test standard of tires is that they must stand 2 to 3 times the reference-pressure.
So dont worry about the high pressure.
What you could worry about is the temperature of the gas compound in the tire, wich is somewhat related to the temperature of the tire material, and related to the pressure rising from cold to warm.

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Not sure what tires you have. Mine have a max pressure of 50 PSI....which, of course, is a cold tire inflation pressure. I inflate mine to the 41 PSI (again, cold tire inflation pressure) recommended by MB. The pressure will go up quite a bit as the tires heat up. Underinflated tires will definitely negatively impact mpkWh.

 

Mine is Bridgestone, 21 inch for EQS 450.
Yes, mea culpa. I was looking at the pressure @ setting the beads. Thanks, jadatis.
hlothery: where can I find the info on the max pressure for the tires?

 

Tirerack.com is pretty much your goto resource for tires. Just search for the exact tire you have, make sure you have the correct load and speed rating and then look at the specs. They give you all the specs of the tire. Strangely, they don't have the EQS 450 in their system yet. Well, it's in their system, but it doesn't bring up any tires for it. The EQS 580 is there with all the tire options. I'm guessing the 450 probably uses the same tires. There are two Bridgestone OE tires listed for the 580. The Turanza LS100, which is an all-season and the Turanza T005, which is a grand touring summer tire. The latter's max pressure is 50 psi, but the LS100 seems to be brand new and the specs haven't been published yet for the 265/40R21 105H, but it comes in other sizes and the max pressure is 50 or 51 psi on those.

 

You are doing the right thing. With OEM tires you should follow the pressure on the door jamb. The max pressure on the sidewall is exactly that a spec that has nothing to do with the correct pressure for a particular vehicle.

 

The max cold pressure is mostly also given on sidewall, but is not that important for the tiremakers, sometimes tgey give on XL with 42psi referencepressure, a max cold of 44psi, wich only leaves 2 psi to highen up for speed and camber angle above 2 degr.

I once got hold of the official calculation for pressure, and went running with it, now call myself " pigheaded Dutch selfdeared tirepressure specialist"

If you give exact sises, and loadindex ( that 105 mentioned) and if XL or not, I can make a pressure/loadcapacity list with reserve added, so you dont need to add that yourselfes.
Then also give the maximum speed you use, and wont go over for even a minute, and I make it for that speed.
Then You"only" have to determine the axleweights, the most tricky part in it all.

 

Usually it is printed in very small print along the sidewall of the tire. That's where mine is, but you will need a flashlight and your reading glasses to find it! It is not a very important number anyway. I would just go with the cold tire inflation numbers on the door sill, as recommended by MB.

 

My size is 265 40R 21 105H Extra Load. Bridgestone.
Thanks.

 

Then I made you this list
loadindex 105 is maxload 2040 lbs a tire.
Using my own determined formula, gives even lower loadcapacity's then the european calculation.
Build in a reserve by using 90% of the loadcapacity calculated for the pressure, and given for the reference speed of 160kmph/99mph.
This is maximum reserve with still acceptable comfort and gripp.
If you want it for other speed or per tire, other reserves, write it, and I change the values in my made spreadsheet.

Given per axle.
And dont add reserves yourselves, and you dont need to devide by 2 for weight on tire, is all done for you.

You could search for Gross Axle Weight Ratings (GAWR's), for that weight the pressure is calculated by the carmaker. But most likely they yust gave the 41 psi referencepressure of a P-tire as standard, so you can never sew them for giving to low pressure.
I now used the 42psi of eurometric tire, nowadays also used in US. In case of daubt always use the highest. Give as high as 60psi, because some XL ( Toyo for instance) give max cold of 60 psi, but set your own border for that.

You yourself stay responcible for the axleweight, and if you drive faster ( but who does) tires can still overheat.
This only has to happen once, and the tire is lost.
Little internal cracks are made then, wich tear further by the mechanical forces in time, whatever you do with the pressure after that, and then mayby after 3 years tire blows or treath seperates, and then the extreme conditions at that moment are blamed.


265/40R21 XL 105H ( or other speedcode above Q)
Weight on axle/ adviced pressure
1395 lbs/ 14 psi /
1478 lbs/ 15 psi /
1562 lbs/ 16 psi /
1645 lbs/ 17 psi /
1728 lbs/ 18 psi /
1811 lbs/ 19 psi /
1894 lbs/ 20 psi /
1976 lbs/ 21 psi / is minimum in european lists
2058 lbs/ 22 psi /
2140 lbs/ 23 psi /
2222 lbs/ 24 psi /
2304 lbs/ 25 psi /
2385 lbs/ 26 psi / is minimum in US lists
2467 lbs/ 27 psi /
2548 lbs/ 28 psi /
2629 lbs/ 29 psi /
2710 lbs/ 30 psi /
2791 lbs/ 31 psi /
2871 lbs/ 32 psi /
2952 lbs/ 33 psi /
3032 lbs/ 34 psi /
3113 lbs/ 35 psi /
3193 lbs/ 36 psi /
3273 lbs/ 37 psi /
3353 lbs/ 38 psi /
3433 lbs/ 39 psi /
3512 lbs/ 40 psi /
3592 lbs/ 41 psi / your recomended
3672 lbs/ 42 psi / is reference pressure used
3751 lbs/ 43 psi /
3830 lbs/ 44 psi / is sometimes maxcold given
3910 lbs/ 45 psi /
3989 lbs/ 46 psi /
4068 lbs/ 47 psi /
4147 lbs/ 48 psi /
4226 lbs/ 49 psi /
4305 lbs/ 50 psi /
4383 lbs/ 51 psi / is often max cold given
4462 lbs/ 52 psi /
4541 lbs/ 53 psi /
4619 lbs/ 54 psi /
4698 lbs/ 55 psi /
4776 lbs/ 56 psi /
4854 lbs/ 57 psi /
4933 lbs/ 58 psi /
5011 lbs/ 59 psi /
5089 lbs/ 60 psi / XL max cold sometimes

 

Is there an online calculator for this?

 

No, this " pigheaded Dutch selfdeclared tyrepressure specialist" made a spreadsheet for making these lists.
In that I use my own determined formula, wich gives lower loadcapacity's then the pretty safe European official formula, I got hold of 2007 and went running with.
Then can give in spreadsheet percentage given of calculated loadcapacity for the load, standard gives 90%.
And I can give for 1 tire/ axle-end, 2 tires/single axle, 4 tires/ dualload axle or tandem-axle.
So give how you want it, and the tire specifications asked in former post, and I make you a list for your tires.
Even can work maximum speed used in it.

 

Thank you for this fantastic resource tip! While TireRack.com isn't present in Sweden, most of the tires they offer for my new-car-to-be are available here. We just don't have such sophisticated selection tools. I really like the interview process, as car/tire usage is SOooo individual. From my point of view, if a tire can achieve exactly what you want, it doesn't matter whether it costs $150 or $400 in the end. It's still a very small amount to pay for such an important component of your car, safety and enjoyment. In general, I have had the impression over the years that tires are remarkably inexpensive here in Sweden. Even cheaper than in the US. Quite paradoxical, as most things are eye-wateringly more $$$$$ here than in the U.S. (Thanks to 25% VAT Tax & environmental taxes)

 

Maybe I should take my car to the recycling center and weigh it. I found this too:
https://overlandracksontario.com/tir...re-calculator/