Tire PSI...

[batever]

I've seen numbers on this (on eng-tips.com, I think...) and if the numbers can be trusted then the laden psi increase for a typical passenger car tyre is a lot less than 1psi. Experimentally, you'd need a very sensitive pressure guage.

Cool, thanks for the info. It makes sense to me that there would be a tiny increase in the pressure, I wasn't sure what was a reasonable guess though; a small fraction of 1 psi makes sense to me.

[93_EXR.]

on my race car i run
LF - 12 psi RF - 34 psi
LR - 28 psi RR - 29 psi

oval track

On my accord
the door says 32 i usualy run withing 28 -> 36 psi depending on what i'm doing with the car and what size of tires

if u run to much psi (50 psi) u will wear the middle of your tires if you run to little (20 psi) u will wear the out sides of the tires.

accords sould run 30-38 psi no more no less.

[Ronald_Type-R]

It usually depends on what tires I'm running...But in average, winter time I usually run 34psi (cold) all around, and summer time I run 40psi front and 36psi rear (both cold). Based from experience they always go up by 2psi by the time the tires warm up..But that depends, on some instances (long road trip for example), I've had them gone up by 4-5psi at one time..Just gotta make sure they stay under the maximum psi on the tire sidewall!

It's amazing how sensitive they are to temperature though..The weather got a bit cooler yesterday (Not that cold, maybe 5 deg Celcius cooler), and the tire pressure on my car dropped by almost 3psi all around!

But with all the summer tires I've tried out so far, I do find that they all grip more at 42psi compared to the 'recommended' pressure aka 32psi or what not..Which is also another reason why I run less pressure for my rear tires...I find that doing so helps reduce understeer even more during tight cornering...And ride comfort is also better when running at 42psi...But I guess that all depends on chassis/suspension as well

Ronald

[johnl]

on my race car i run
LF - 12 psi RF - 34 psi
LR - 28 psi RR - 29 psi

oval track

Irrelevant. I run between 15 and 22psi in my race kart, but that's not useful information in this context either.

On my accord
the door says 32 i usualy run withing 28 -> 36 psi depending on what i'm doing with the car and what size of tires

Quite reasonable if that's what you wish to do.

if u run to much psi (50 psi) u will wear the middle of your tires if you run to little (20 psi) u will wear the out sides of the tires.

Possibly in extreme cases (as perhaps in your 50psi example), but it's much less of a problem than most people seem to think, a notional hangover from the days of cross ply tyres that were quite susceptible to wearing the middle of the tread with excessive pressure. Radial tyres are much less likely to wear this way because the tread is so much stiffer than a cross-ply tread.

As a specific example I've run radial tyres on the rear of my Accord (i.e. the light end) at 44psi with very even tread wear, certainly not more in the middle of the tread, but more even wear across the whole tread tapered toward the inside due to slight camber. In fact I've never had any problem with radial tyres wearing in the middle, no matter what psi I use, however I have seen plenty of tyres with substantial edge wear sue to under-inflation.

accords sould run 30-38 psi no more no less.

I've run 44psi in some tyres with zero issues beyond increased ride harshness (these specific tyres had more issues at lower psi), most tyres in my experience seem to be better at around 40psi.

IMO your stated pressure parameters may be roughly applicable to some tyres, but are arbitrary and categorical and won't apply to all tyres (which isn't to imply that keeping within those bounds will cause any problem).

Please note that the tyre placard affixed to my CB7 states; "for sustained high speed - 270kpa" (front tyres). 270kpa = 39.160189262psi. This is a cold pressure recommendation and is very close to the psi that I've empirically found to work extermely well with most tyres I've used (if you don't mind the harsher ride quality). When warm I'd expect to see a psi increase from 40psi to around 44psi.