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Tyre pressure


Mllcg
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I'm not sure what your question is, bro. Different manufacturers and different tyre models lor. But unless you pump till damn hard (eg, 38 psi in your example), you won't be maximising that load capacity. And at lower pressure, the load capacity of your stock tyres and PSS are identical, assuming they are of the same size.

 

Go & read the part i highlighted in red.

 

38psi is the minimum pressure,  right?

 

If size is the only determinant, why different manufacturers have diff load index?

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This is the unconfusing part.

The confusing part is

 

 

Example,

Two Standard tyres

Same size

Same pressure (e.g. 32 psi)

One load index is 91 and the other 94.

The load capacity the same?

Yes. The load capacity would be the same until you hit a high enough tyre pressure for the higher load index to matter.
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Go & read the part i highlighted in red.

 

38psi is the minimum pressure, right?

 

If size is the only determinant, why different manufacturers have diff load index?

Sorry man, I'm still not sure what you're saying.

 

Size is NOT the only determinant.

 

A stronger/thicker (also heavier) tyre structure facilitates a higher load index. Two tyres of the exact same size can have different load indices because one can be built tougher (thicker walls, etc) than the other, and therefore function effectively at a higher tyre pressure. At this higher tyre pressure, it will then be able to carry a heavier load than a different tyre of the same size but with a less heavy-duty construction.

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Yes. The load capacity would be the same until you hit a high enough tyre pressure for the higher load index to matter.

 

 

If the load capacity is the same,  can I find out how to explain the following from the load inflation table? 

 

Load Index 91,  32 psi,  1224 lb

Load index 94,  32 psi,  1290 lb

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If the load capacity is the same, can I find out how to explain the following from the load inflation table?

 

Load Index 91, 32 psi, 1224 lb

Load index 94, 32 psi, 1290 lb

Sorry, which specific table are you referencing? Can share the URL?
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Sorry, which specific table are you referencing? Can share the URL?

 

Eh... i PM'ed you.  I scared later I post here, the site crashed and then I no longer can access it !   [laugh]

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Sorry everyone, I was wrong, with apologies especially to @Davidtch.

 

My info applies only to the P-metric tyres mainly used in USA (tyre size starts with "P", eg P225 instead of 225), but not to the ISO-metric tyres we usually use here. I'd assumed the standards were similar and didn't check the data properly. Sorry for the confusion.

 

ISO-metric tyres of the same size, but different load indices, do have different load capacities at different tyre pressures; even relatively low ones. And standard and extra load tyres of the same size, but different load indices, also have different load capacities at different tyre pressures.

 

So please disregard what I've said unless you use P-metric tyres, and instead refer to the attached ISO load index tables here (thanks @kklee for politely correcting me).

 

Sibei paiseh.

 

 

post-75606-0-02809800-1498352278_thumb.png

post-75606-0-43673500-1498352285_thumb.png

post-75606-0-81558500-1498352292_thumb.png

post-75606-0-71351000-1498352299_thumb.png

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Additional information. 

 

ISO Metric (Metric or Hard metric) vs. P-metric

 

It is important to know which standard is applicable for any given tire size designation as the load capacity may differ at any inflation pressure value. The TRA developed the P-metric standard and the ETRTO developed the ISO Metric/Hard Metric standard. For example, TRA P225/55R17 95T has a maximum load capacity of 1521 lbs. @ 35 psi (see Table 1) while 225/55R17 97T has a maximum load capacity of 1609 lbs. @ 36 psi (see Table 2).

 

Note: The load index (e.g. 95) is a numerical code associated with the maximum load a tire can carry at the speed indicated by the tire’s speed symbol (e.g. ‘T’) under certain specified service conditions.

 

Tires with the same load index, regardless of tire size, may carry the same load, but not always, and they may require substantially different inflation pressures. The load index may not be used independently to determine replacement tire acceptability for load capacity.

 

An equal or greater load index does not always correspond to equal or greater load capacity at all inflation pressure settings, particularly when comparing P-metric and Euro-metric passenger car tires.

 

 

Source - Toyo Guidelines for the Application of Load and Inflation Tables

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No worries @muser.  We learn from each other in the forum.

 

@kklee good work on the research.  From zero to now able to understand load index [thumbsup]

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@kklee good work on the research.  From zero to now able to understand load index [thumbsup]

 

Next, we will relate it to the contact patch follow by the cold tyre pressure !   [laugh]

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My car manufacturer sticker stated both front and back, no load and full load recommend tire pressure is 32psi. I just measure all the tires (cold reading) is about 38psi! Recently changed tire and pump by tire shop. No wonder I feel the car like a bit slippery.

 

This recommended pressure reading is suppose to be taken without load in the car right?

I mean when the recommend 32psi for full load, they don’t mean u take the reading when your car is fully loaded right?

 

So should I decrease the pressure back to 32psi?

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My car manufacturer sticker stated both front and back, no load and full load recommend tire pressure is 32psi. I just measure all the tires (cold reading) is about 38psi! Recently changed tire and pump by tire shop. No wonder I feel the car like a bit slippery.

 

This recommended pressure reading is suppose to be taken without load in the car right?

I mean when the recommend 32psi for full load, they donât mean u take the reading when your car is fully loaded right?

 

So should I decrease the pressure back to 32psi?

if you feel the car is a bit slippery, can deflate a bit. i usually pump slightly above the recommended pressure, but this depends on personal preference.
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Hi.. just asking.. how to check what pressure to pump for my tyre. Im driving a toyota vios. 16 inch

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2.2bar

220kPa

 

If one is lazy to pump and check frequently, then can pump 2.6bar.

Then only need every three months pump one time.

 

If still very very very lazy and don't bother type.

Just ask the pump attendant to pump the standard pressure whenever at refilling station.

 

 

 

 

 

Hi.. just asking.. how to check what pressure to pump for my tyre. Im driving a toyota vios. 16 inch

 

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Hi.. just asking.. how to check what pressure to pump for my tyre. Im driving a toyota vios. 16 inch

U open your driver side door, 

 

see the inside lock there. 

 

all the orginal tyres size and recommended pressure writting should be there.

 

anw if cannot find, 240+- wont go wrong

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