How much would the air pressure increases if driving for long hours during the hot day? It should be about 4-6psi?

My rule of thumb is about 4 psi.

So if max allowed is 51psi, max air pressure can put is 47psi. Anyways, 40+psi is already on the high side dy. I usually pump 31front/28back.

Will try pump more and see the effect on driving/braking

Update on my earlier post...

I pumped 34front/32back.

Car feels more agile, but rattles/shakes more. Braking distance increases, and feels less safe (lesser contact to ground?). Fuel economy-wise, hard to guess. Macam no significant difference

For sedan, does it make sense to pump same air pressure for both front and rear?

My Avanza specifies 31 front and 35 rear.
I pumped 38 psi, and now 41 psi on all four tyres ...........................
for its maximum tyre loading and maximum tyre road speed which isn't required for the Avanza, but fine for the tyres anyway.

This post has been edited by zeng: Feb 21 2018, 10:52 AM

Must be epic bouncy

What are you aiming for in pumping more than the recommended air pressure? Is it fuel economy and/or lesser frequency to pump air and/or fuel economy? Curious to know

More for agility ... and then for fuel economy, yet stay within specs of tyres in question.
Also note tyre pressure drops by about 3 psi in every 1-1.5 month of use .

... not really with good road surface in KL/Subang Jaya areas, other than safety bumps within Taman where I typically move at 15-25 km/hr.

Fair enough. Anyway, no significant longer braking distance?

Longer, yes.
Significant, no .

u want comfort, u pump air near to oem spec (always more, never less than oem spec)

oem pressure is their tested pressure which gives best comfort without sacrificing performance (or issit the way around, forgot). usually la.

u want best performance, u pump higher pressure, but never exceed max load pressure by tyre manufacturer. u need to find the best sweetspot for ur car. meaning experimenting urself. theres no 'one pressure to rule em all' for this. deswai race car oso need to find their right tyre pressure for every track, sometimes right pressure means 1-2 sec difference in lap time.

higher pressure gip better performance (grip, fuel economy, less rolling resistance (last one im not sure ) but ull be sacrificing alot on comfort.

This post has been edited by kurangak: Feb 22 2018, 08:47 AM

Maybe the additional ride height/suspension travel mask the harshness quite well.

I did something similar to my sedan, quite close to maximum recommended, and the car feels like it was on adjustables set to harder setting. So i dial down 10-15kpa for my preferred setting.

Less rolling resistance and better grip? Wont less rolling resistance means less grip?

If manufacturer recommends 32front/30back, make sense to put front/back to 32psi?
Both front/back tyres same size

Yes if you are carrying passenger + luggage.

Mine front and rear ate diff profile but I pump same 35 psi! The car feel lighter. Lol!

! What's your tyre profile? Most is 15 inch rite ? 38 psi?

185/70R14 88H tyres.