Hi,
Last night I filled air on my tires but by mistake I filled around 39 PSI on one of the tire instead of 35 PSI which was maximum allowed on this tire. I was surpirsed to see that as when icheck it physically then it looks like it has lack of air on it but my air gauge showed that it is 39 PSI.
I am curious as to what are the consequences of over inflating the tires and will it adjust automatically after releasing some internal air or do I have to do it manually.
Please let me know.
Thanks.

 

For the amount of time that it was overinflated, there will be no consequences. If the condition had gone undetected, tire wear would have been concentrated on the center of the tread pattern (rather than evenly across) and it would have worn out faster.

P

 

I run all my tires at 10 psi above the max rating in an effort to get better gas mileage and have seen only minimal indicators of increased wear in the center. All in all, the increase in gas mileage and $$ savings is greater than the cost of replacing the tire due to minimally increased wear.

I imagine in a heavier car there's a greater amount of wear but in light cars like ours, it just doesn't seem to make that much difference.

 

P,
When was the last time you actually saw a tyre worn significantly more in the centre than at the edge or edges? Last time I saw it was years ago on cross ply tyres (aka bias belted).

Steel radials just aren't very prone to crowning (and resultant centre tread wear) because the belts provide a lot of stiffness across the tread. Cross ply tyres on the other hand are very prone to it because the tread is far from stiff.

To create significantly greater centre wear on a typical radial will usually require a very substantial inflation, significantly higher than the max psi on the sidewall. However, higher pressures will tend to mean that if camber is too far from zero then more wear will tend to occur on the tread shoulder or tapered across thhe tread. A similar affect may occur with stiffer casings, i.e. shorter sidewalls and / or stiffer sidewall (i.e. less angled ply cords or more sidewall cord plies).

If pressure is very high (enough to cause significant crowning), then crowning and centre wear may well be more severe with a wider width tread than a narrower tread because the wider the tread the less 'beam' strength the tread has from edge to edge (all else being equal).

The OP states; "35 PSI which was maximum allowed on this tire", but I suspect he means the car placard, not the max sidewall psi. It's likely that the max sidewall psi is either 44psi or 51psi, so, if I'm correct, 39psi isn't particularly high for that tyre and the tyre will suffer no damage, assuming camber isn't excessive.

Other consequences of 39psi vs 35psi will most probably include; improved steering and handling response, improved grip, improved fuel economy, improved tyre life, cooler running temperature, less pressure rise in use, harsher ride quality, somewhat decreased resistance to being punctured by large sharp objects.

I commonly run 40psi to 45 psi in my stock (CB7) sized 195/60/15 tyres with no problems at all...

 

Well, considering I grew up with bias Belted tires (Tyres to faux Brits) and very much welcomed the introduction of Radials, I'm by no means a "spring chicken" and I hope that you will allow me to speak in generalities (which I did here).
I'll just leave it with; decreased traction on marginal surfaces, unpredictable responces during suspension upsets, excessive rebound as the tire bounces over bumps as opposed to absorbing the shock, and yes - given enough time, predictable wear (tire compound sensitive)

again: [quote] "For the amount of time that it was overinflated, there will be no consequences." [quote]

 

P,
"faux Brits"... in Australia, people have died for less!!

I learned to drive on cross ply tyres (I'm 49), and raced on them (karts).

You say; "decreased traction on marginal surfaces". Higher psi does tend to be less grippy (i.e. more slidey) on loose marble surfaces, but I've had no concerns on 'non marbly' dirt roads, or in the wet.

And; "unpredictable responces during suspension upsets". I don't agree, not in my experience.

And; "excessive rebound as the tire bounces over bumps as opposed to absorbing the shock". To some degree I do agree, tyres act as springs and have a 'spring rate', but are almost completely undamped (there is some internal damping action, but it's minimal).

Even at 'normal' psi the tyre 'spring rate' is very high and the range of 'spring' motion very small, so I suspect this is only a significant problem if the dampers (shocks) are marginal (either worn or quite soft as stock). At higher psi more force is passed through the stiffer tyre case into the 'real' suspension, and ride will be somewhat harsher, but handling will only be adversely affected on rough surfaces and if the dampers are either weak, or set way too stiffly.

"For the amount of time that it was overinflated, there will be no consequences." I can't possibly disagree, but my point is that if the psi were left at the higher psi figure permanantly then it would still be highly unlikely that any damage would occur, and the tyres may even wear a bit better.