Why is the Tire Pressure so High

"punkgoose17" (punkgoose17) 05/31/2018 at 08:46 • Filed to: Tesla, Tesla Model 3, Tire Air Pressure, Tire Pressure

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I’ve never seen higher than 32 psi on a tire pressure tag. Are newer cars running higher pressures for better fuel economy? Is this a common thing for low profile tires? What are your experiences?

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Ash78, voting early and often > punkgoose17 05/31/2018 at 08:54

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All of our tires have a max psi on them (45-50), but if you open the fuel door or look inside the door jamb, there’s usually a calculation about expected load and speeds and WE DONT NEED NO MATH THIS IS AMERICA

CalzoneGolem > Ash78, voting early and often 05/31/2018 at 08:58

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MURIKA ALWAYS TAKES IT TO THE MAX!!!

MonkeePuzzle > punkgoose17 05/31/2018 at 09:00

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is it possible that it is specific to the Tesla product line, as I know because of the batteries they are very heavy and have specially designed wheels and likely tyres also?

JQJ213- Now With An Extra Cylinder! > punkgoose17 05/31/2018 at 09:00

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38 psi is actually the recommended amount on the door jamb in my 2013 Volvo. It rides on 235/40/18

RutRut > punkgoose17 05/31/2018 at 09:01

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Currently rolling around at ~60-65 PSI on my F-250, rides awful. Could be the “E” load rated tires, or the unloaded truck with leaf springs.

punkgoose17 > Ash78, voting early and often 05/31/2018 at 09:02

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I don’t think I ever noticed an equation. I usually see one set of pressures for medium load and one set of pressures for max load, and I adjust accordingly.

pip bip - choose Corrour > punkgoose17 05/31/2018 at 09:03

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never noticed

someassemblyrequired > punkgoose17 05/31/2018 at 09:03

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Reduces the tire contact patch, and rolling resistance, therefore better range.

facw > punkgoose17 05/31/2018 at 09:05

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My 2006 Volvo S60 recommends 38 all around. There’s an alternate pressure that I think is something like 32 front 30 rear, but warns that it will hurt fuel economy and greatly reduce the maximum load.

In any event, I suspect you are seeing higher recommended pressures so that manufacturers can claim higher fuel-economy. Also the Model 3 is heavy for its size due to the batteries, which probably makes it necessary to boost the pressure as well.

PartyPooper2012 > punkgoose17 05/31/2018 at 09:10

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had tires mounted on rims by a shop. They jacked up the pressure in there to 42. When I got home and mounted the wheels on the car, all sorts of bells and whistles went off that the pressure is too high. According to door jamb, cold pressure should be at 30. Been watching the pressure go up as tires warm up by 5-6 PSI.

E90M3 > punkgoose17 05/31/2018 at 09:12

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My M3 has two recommended tire pressures, one for speeds up to 100 mph, one for speeds above 100 mph because autobahn.

Ssfancyfresh > punkgoose17 05/31/2018 at 09:15

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2014 Audi A4 - 38 PSI

Seems about right

TorqueToYield > punkgoose17 05/31/2018 at 09:21

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Fuel economy and in Tesla’s case electric range.

Newer cars are pushing pressures upward.

I assume the tires they use are specifically designed for these pressures.

Frenchlicker > punkgoose17 05/31/2018 at 09:23

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Most tires I’ve seen say around 44 max. So I guess it makes sense for a car to be similar.

fintail > punkgoose17 05/31/2018 at 09:30

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I think the stock runflats on my DD are made from solid rubber like on a truck from 1915, so no worries there.

OpposResidentLexusGuy - USE20, XF20, XU30 and Press Cars > JQJ213- Now With An Extra Cylinder! 05/31/2018 at 09:31

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It’s also SWEDISH RACING GREEN.

AMGtech - now with more recalls! > punkgoose17 05/31/2018 at 10:06

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Pretty common. Higher pressures prevent pinch flats and improve tire stability. Most current AMG’s run upper 30's to mid 40's.

SmugAardvark > punkgoose17 05/31/2018 at 10:08

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My C5 recommends 30psi, and the Cube recommends 33psi.

More pressure clearly means more performance, and the Cube must be the ultimate sleeper beast.

Nibbles > punkgoose17 05/31/2018 at 10:09

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My Ram’s TPMS screams if a tire drops below 39 PSI. Keeping a truck at 40 or better is just weird to me

Out, but with a W - has found the answer > punkgoose17 05/31/2018 at 10:13

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On my ND MX-5 it’s 29 psi, my MR2 was 26 in the front (I feel slightly dirty using psi instead of bar/kPa). Yay for lightness!

diplodicus > E90M3 05/31/2018 at 10:15

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As long as you don’t bring a book with you, you don’t need to change the pressures. That is how I interpret this diagram. 

bob and john > punkgoose17 05/31/2018 at 10:18

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our Audi A3 etron runs 41 PSI all 4 corners. our old A3 TDI ran 42 front, 37 rear.

not sure what the GLK runs. I think its 39 front, 33 rear

Textured Soy Protein > punkgoose17 05/31/2018 at 10:21

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The door jamb tag on my 335xi specifies 35 psi front and 39 psi rear.

BigBlock440 > Nibbles 05/31/2018 at 10:34

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Trucks are different animals, especially HDs, which run upwards of 85 psi if hauling. I run 55 in my 1500.

HammerheadFistpunch > RutRut 05/31/2018 at 10:52

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All of the above. If your truck weighs less than 3 tons empty drop em down. I have e rated on my cruiser. It weighs 5500 without me and I have mine at 33

jimz > punkgoose17 05/31/2018 at 10:56

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recommended tire pressures (what’s printed on the door plate) is based on the load carrying capability of the tires and the vehicle’s GVWR and the best feasible for max fuel economy/range. The pressure embossed on the tire sidewall is the maximum the tire manufacturer is willing to stand behind at the stated load rating.

varying pressure ranges aren’t uncommon; the load range “E” tires I had on my old F-250 were recommended to be (IIRC) 40-50 psi unloaded, up to 80 at max GVWR.

merged-5876237249235911857-hrw8uc > punkgoose17 05/31/2018 at 11:04

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My car calls for 38-44psi depending on the loading.

haveacarortwoorthree2 > punkgoose17 05/31/2018 at 11:25

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All this hand-wringing over tire pressure. Who cares! It really doesn’t matter — I drive all the time with one tire a little lower than the other and nothing has ever happ.............

RutRut > HammerheadFistpunch 05/31/2018 at 11:28

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Last time I dropped stuff off at the scrap yard on the way out I was ~7200lbs with me in it (~235lbs). But it is most likely getting traded in tonight for something else with a terrible ride.

HammerheadFistpunch > RutRut 05/31/2018 at 11:40

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consistency is underrated.

red014 > punkgoose17 05/31/2018 at 11:41

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Probably not low profile, my Miata rides on 205/45R17 and the recommended pressure on the door sticker is 29 psi. I’d imagine it’s for rolling resistance. Higher psi = less sidewall and tread flexing.

RutRut > HammerheadFistpunch 05/31/2018 at 11:53

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Still 4 doors, still 4 driven wheels, still bad fuel economy and still a garbage ride and interior quality. F-250 to STI is a surprisingly consistent transition minus like 3500lbs and 4 cylinders.

I like cars: Jim Spanfeller is one ugly motherfucker > punkgoose17 05/31/2018 at 12:10

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My mom’s BMW 3 series is at 37/41 front/rear. I think the spec is like 38/42. It’s what you get with low profile tires. If you put them at 32 or so as you would with a tire that actually has sidewall, you’ll get flats every time you hit a pothole.

Mercedes Streeter > punkgoose17 05/31/2018 at 12:57

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I set my pressures to 5 psi under max (50 is the max on my current tyres) and forget about it. For whatever reason, smarts seem sluggish and sloppy when you have much lower pressures.

punkgoose17 > Mercedes Streeter 05/31/2018 at 13:32

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Maybe the tire pressure was tuned to understeer? I decreased the pressure in the rear of my VW so it felt more neutral / less understeer.

wafflesnfalafel > punkgoose17 05/31/2018 at 21:53

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I kept getting low tire warning on my wife’s car until going to 35psi all the way around....