When I checked my tires the next morning
RF-40
LF-35
Rears were around 32.5
should be 33 front, 32 rear according to door jamb
Vehicle Manufacturers Tire Pressure Recommendation
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RF-40
LF-35
Rears were around 32.5
should be 33 front, 32 rear according to door jamb
My E-Golf is 40PSI at all 4 corners - ride quality does not seem to suffer at all so thinking the pressures are to counteract the heavy batteries. Even at 40PSI the 205/55/16 Bridgestone Ecopia tires still have a slight bulge at the bottom and the car actually rides pretty nicely.
My old '12 MB E350 had conflicting tire pressures between the door jamb and the gas door (maybe it was gas door, or owners manual). The door jamb was higher than even the "high speed" tire pressure recommendation. I just let Discount Tire go with the door jamb and didn't argue.
My old '12 MB E350 had conflicting tire pressures between the door jamb and the gas door (maybe it was gas door, or owners manual). The door jamb was higher than even the "high speed" tire pressure recommendation. I just let Discount Tire go with the door jamb and didn't argue.
The 205/55R16 is made in standard load , LI 91 is maxload 615 kg AT 36 psi upto 160kmph, and LI 94 is maxload 670kg AT 42 psi upto 160kmph.
Li 91 would cover an axle-load of 1230 kg best use 90% of that so 1107 kg AT 36 psi
Li 94 same story 1340kg AT 42 psi 90% 1206 kg.
The 90% for upto 160kmph/99mph, I determined to give still acceptable comfort and gripp. But on smooth roads comfort stays OK with lower %.
So fill in yourselfes if your axleloads are about the weights given, and check if you have XL/reinforced/extraload.
To high pressure is not bad for the tire, only can give sooner punctures.
Li 91 would cover an axle-load of 1230 kg best use 90% of that so 1107 kg AT 36 psi
Li 94 same story 1340kg AT 42 psi 90% 1206 kg.
The 90% for upto 160kmph/99mph, I determined to give still acceptable comfort and gripp. But on smooth roads comfort stays OK with lower %.
So fill in yourselfes if your axleloads are about the weights given, and check if you have XL/reinforced/extraload.
To high pressure is not bad for the tire, only can give sooner punctures.
One item that hasn't been discussed yet is that the spring rate of a tire is affected by its inflation pressure. Change the pressure and you can change the handling balance of the car.
Also, the spring rate curve of a tire is more or less than same regardless of the make and model of the tire.
So the inflation specified by the vehicle manufacturer on the Vehicle Tire Placard is what the vehicle manufacturer tested to set the spring rate, the shock damping, and the sway bar size - and it applies regardless of the make and model of tire.
That's one of the reasons why NASCAR drivers can feel 1/2 a psi difference - it affects the balance of the car (that is, which end is loosing grip first).
Also, the spring rate curve of a tire is more or less than same regardless of the make and model of the tire.
So the inflation specified by the vehicle manufacturer on the Vehicle Tire Placard is what the vehicle manufacturer tested to set the spring rate, the shock damping, and the sway bar size - and it applies regardless of the make and model of tire.
That's one of the reasons why NASCAR drivers can feel 1/2 a psi difference - it affects the balance of the car (that is, which end is loosing grip first).
I know its pigheaded to disagree with a profesional like Capri Racer, but I dont believe that vehicle makers do severe testing on tirepressure. To my idea they yust give the tiremaker axleweights and speed used, and tiremaker gives advice pressure for that.
Mayby they then do a little drive around the church, but no more.
For electric cars and bicycles the yust go extremely high in pressure advice, only to give the battery a higher actiradius, and later in next model, they come back from that a little, because of wear a comfort complains.
Mayby they then do a little drive around the church, but no more.
For electric cars and bicycles the yust go extremely high in pressure advice, only to give the battery a higher actiradius, and later in next model, they come back from that a little, because of wear a comfort complains.
Sorry Jadatis, but I have personally witnessed a little of the severe testing that the vehicle manufacturers do. I stood by the side of the road course while a fully loaded E-350 smoked its tires around the curves. 10,000# of Van doing high speed handling maneuvers is pretty scary stuff!
The procedure that all the vehicle manufacturers follow is to issue a document with the tire requirements - usually in the form of tests. They specify the size and inflation pressure as part of that document. It is usually issued 2 years before the first tire is supposed to arrive at their assembly plants. --Yes, it takes that long!
On completely redesigned models, the Ride and Handling Engineers spend a lot of time with spring suppliers, shock suppliers, and sway bar suppliers - not to mention suspension bushing suppliers, axle suppliers, etc. - to select those components that get the target ride and handling. This takes a long time and a lot of work on the handling courses - which is why vehicle manufacturers have Proving Grounds in warm weather locations (so they can test year round).
Now maybe bicycle manufacturers and wheelchair manufacturers don't do severe handling maneuvers, but the major car and truck manufacturers certainly do.
Do tire manufacturers do severe handling testing? Yes, they do - and at the pressures specified by the vehicle manufacturers.
I have more info on this page: Barry's Tire Tech: OE Tires
The procedure that all the vehicle manufacturers follow is to issue a document with the tire requirements - usually in the form of tests. They specify the size and inflation pressure as part of that document. It is usually issued 2 years before the first tire is supposed to arrive at their assembly plants. --Yes, it takes that long!
On completely redesigned models, the Ride and Handling Engineers spend a lot of time with spring suppliers, shock suppliers, and sway bar suppliers - not to mention suspension bushing suppliers, axle suppliers, etc. - to select those components that get the target ride and handling. This takes a long time and a lot of work on the handling courses - which is why vehicle manufacturers have Proving Grounds in warm weather locations (so they can test year round).
Now maybe bicycle manufacturers and wheelchair manufacturers don't do severe handling maneuvers, but the major car and truck manufacturers certainly do.
Do tire manufacturers do severe handling testing? Yes, they do - and at the pressures specified by the vehicle manufacturers.
I have more info on this page: Barry's Tire Tech: OE Tires
All you can do is try and keep it near the OE pressure range as much as you can. Way to many variables if you want to have the perfect tire pressure. If you want to split hairs, use a tire temperature gauge, and adjust your tire pressures every few hours or so, and try and keep it within a 1/2 pound of perfect..
Reaction to post #46 of Capri Racer.
Read your article, and what puzzles me is how in the beginning the vehicle manufacturer determines the pressure for the tiresise they give the tire-manufacturer. And if in the proces, this stays the same, or is open for discussion.
Read your article, and what puzzles me is how in the beginning the vehicle manufacturer determines the pressure for the tiresise they give the tire-manufacturer. And if in the proces, this stays the same, or is open for discussion.
OE tire pressure also tied to vehicle dynamic handling in emergency situations. That's something most people never practice before it's too late, including myself. Years of auto-crossing has helped me a lot, and should be a requirement in driver training from my experience.
As I recall during the Ford/Firestone tire fiasco, Ford recommended 20 PSI in the infamous Wildnerness A/T tires to compensate for the suspension roughness on the Explorer to resolve testing complaints.
Same tire despite the disputed deficiencies in manufacturing was put on other SUVs of the same weight such as the Jeep Grand Cherokee where it was 35 PSI.
Same tire despite the disputed deficiencies in manufacturing was put on other SUVs of the same weight such as the Jeep Grand Cherokee where it was 35 PSI.
While I hesitate to repeat the factual errors in this post, I need to have the reference.
First, It was the Firestone ATX that started that mess. The Wilderness AT came later, but was also recalled for essentially the same reasons.
Second, the tires on the Ford Explorer were UNIQUE and NOT supplied to any other vehicle manufacturer.
Third, the pressure was 26 psi, which was enough to cover the weight, but just barely - but that was common for the SUV's of the era. No one does that now. Ford did that to help tipover resistance.
Here's my take on the subject: Barry's Tire Tech: The Ford/Firestone Controversy
As a former owner of one of those Explorers, on which the tires were replaced for free under the safety/recall campaign, I assure you that your recollection is a bit off.
The owner’s manual for that vehicle did, in fact, state 26 PSI. I never ran it that low as the handling was mushy (well, to be fair, the handling was still mushy regardless of pressure, even after I put on new shocks).
Please read CapriRacer’s post.
The bigger issue IMO was not necessarily the spec 26psi, but people not maintaining their tire pressure, or owning a gauge. So you have all of these people flying down the highway, fully loaded running 20 psi because they don't have a clue, which wouldn't even turn on the low tire pressure warning if they had it. Even now, too many drivers out there drive with the light on not knowing what it means, or even care. Almost everyday you see cars by the side of the road with a flat spare tire, and a junk tire in the trunk that also got destroyed from low pressure. The only way TPMS could have solved the problem would have been to shut the car down when the light came on.
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I always buy premium tires so that might also be the reason why i dont have ever had any isues. (Except for a car that i bought with crap tyres and failed on me with correct pressure with the inner cords breaking)
On my bmw with 225 40 18 front and 255 35 18 rear i always start with the manufacturer spec.
I closesly monitor the pressure before long trips and also when there is a large difference in outside temp compared to last time.
After the tyres are more worn i monitor them and i slightly increase or decrease the pressure to help the tyre wear more even.
With prolonged 120mph/180kmh trips the center of the tyres tend to wear out due to the centrifugal forces but this is not really compensateable and depends more on which brand.
Also be aware that atleast in Holland official car dealerships Michelin approved and yearly inspected/tested tyre gauges are allowed to have a maximum amount of 20% difference compared to the calibration device.
So when i use one of those there could already be a MAX 20% higher or lower difference. When i then measure with a cheap one there is about a 10% a 15% difference compared to the michelin gauge.
So in reallity it cold be a 30% a 35% DIFFIRENCE!!!
So investing in a good gauge is always good point to start.
On my bmw with 225 40 18 front and 255 35 18 rear i always start with the manufacturer spec.
I closesly monitor the pressure before long trips and also when there is a large difference in outside temp compared to last time.
After the tyres are more worn i monitor them and i slightly increase or decrease the pressure to help the tyre wear more even.
With prolonged 120mph/180kmh trips the center of the tyres tend to wear out due to the centrifugal forces but this is not really compensateable and depends more on which brand.
Also be aware that atleast in Holland official car dealerships Michelin approved and yearly inspected/tested tyre gauges are allowed to have a maximum amount of 20% difference compared to the calibration device.
So when i use one of those there could already be a MAX 20% higher or lower difference. When i then measure with a cheap one there is about a 10% a 15% difference compared to the michelin gauge.
So in reallity it cold be a 30% a 35% DIFFIRENCE!!!
So investing in a good gauge is always good point to start.
I'm sure I posted a reply to this, but now, I can't find it. So if this is a repeat - Sorry!
It's easy to figure out beforehand what each corner of a proposed vehicle is going to weigh. This was true way before the days of computers and computer modeling.
Therefore, it's easy to select a tire size and inflation pressure that will hold up that load. It would also have been known how vehicles behaved in the past and that could be used to predict what a new model would do.
Then it's a matter of just verifying that the vehicle does nothing unpredictable - and adjusting accordingly.
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Just did the same thing on the Rubicon … pillar states 37 … dealer had 38/39 … was reading up on solutions to “Jeep wander” … some said try 35 … slight improvement on steering but certainly a better ride.
The 285’s are fairly “crowned” compared to E rated in same size and at 35 there’s not an unusual flat spot so will keep an eye on them and enjoy.
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Depends on the vehicle and what I am doing with it. The Jeep could be running 35 or 20 or something in between for different surfaces--road, rocks, or sand. If aired up to the 37 PSI rating on the door pillar, you will be guaranteed the bounciest ride on a highway known to man.
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You sure you want to put E’s on it … ?
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