Increased fuel economy from over-inflated tires

**niky** · December 5th, 2011 04:09 PM

The extra pounding from stiff tires is not quite as bad as the extra pounding you get from using heavier mags or lowering springs... but yes, it causes extra stress.

Which is why the next step is to get better shocks.

One situation where over-inflation is bad is where you've exceeded the suspension's ability to control the tire and it skips or bounces under braking.

Originally Posted by glenn manikis

sir i use a yokohama geolandar ht... 245 70r16 tires... its max. inflation reads 51psi... and the sticker on my front dr. reads 45psi unladen, and 55psi laden...
sir can i use 55 psi on it?

sir may nakausap po ako dati na technician or engineer ata yung sa isang tire factory... ang sabi kasi nya sakin ... mas mataas ang hangin mas matibay pa nga daw ang tires... ang dahilan daw po nito eh... para daw po kasing filler ang air... so mas maraming filler mas matibay.... im not sure pero ang pagkakatanda ko yung gulong nga daw na may max inflation ng 60psi.. kung i-test nila eh they put up to 95psi on it... to check kung may leak daw... or force ply ata yun... then may nabangit din po sya na meron daw 5psi na allowance pa daw yun sa max na recommended na naka indicate sa tires... sir again im not sure po ha.... at may 13years na po ata yun... sir i want to know if it is true...?

Tire Explosion - YouTube
^^^
That tire was rated for 90 psi. 300 before she blew. I think you will be okay with just four psi over the max sidewall pressure, but I cannot be responsible for telling you that it's okay to exceed the manufacturer's rating. Especially considering our rough roads here.

**uls** · December 5th, 2011 04:39 PM

air in tires = cushion = absorb impact forces like accidentally driving into deep potholes

rock hard tires = almost no cushion = impact forces fully transferred to suspension and chassis

oh well...

**Noel Salisipan** · December 7th, 2011 11:34 AM

"That tire was rated for 90 psi. 300 before she blew. I think you will be okay with just four psi over the max sidewall pressure, but I cannot be responsible for telling you that it's okay to exceed the manufacturer's rating. Especially considering our rough roads here.

"[/QUOTE]

It is not advisable to use more than the PSI requirement, it is for tire factor of safety (FOS). And more than 80% rated capacity is reserved for tire during abnormal situation, and for your personal safety!
Say, 90PSI rated capacity. 80% of it is 72PSI. Therefore, safest PSI is 72 and below...

**glenn manikis** · December 7th, 2011 01:06 PM

salamat sir niky.... the tire blew at 300psi (rated lang up to 90 psi) or more than 3x the maximum rating sa tires and the temperature is at 1181 degrees F pa!!! talaga palang sasabog yan...

try ko over ng 4psi...

**niky** · December 7th, 2011 01:51 PM

Originally Posted by uls

air in tires = cushion = absorb impact forces like accidentally driving into deep potholes

rock hard tires = almost no cushion = impact forces fully transferred to suspension and chassis

oh well...

That's the best reason to NOT overinflate. But it depends on the tire and chassis in question. On passenger cars, we usually don't inflate to more than 30-40 psi. On some trucks, normal inflation pressures are around 100 psi. 40 psi to 50 psi for a cargo truck isn't really rock hard.

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As for "Factor of Safety", due to liability concerns, that FOS is already built into the sidewall maximum pressure. In other words, the maximum sidewall pressure is not the absolute maximum, but a low rating that should keep the tire from bursting under continuous usage conditions short of 50 degree Celsius heat with an overloaded vehicle.

Why is the sidewall maximum low? To prevent lawsuits and liability. If you actually stated the bursting pressure on the sidewall and somebody inflates to one psi over that and experiences a blowout, then the tire manufacturer is liable for it.

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Again, while I say I personally believe just four over is safe, I cannot guarantee it is, and if the tire is old or has damage, better not to risk it. Personally, I'd just get a tire that's rated at over 50 psi and use that instead, as it's also bound to be more durable than the one that isn't.