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KrazyKong

Possibly Serial Offender. Do I Keep Pumping Up My Tyres Too Much?

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I've always been a person who likes to have their tyres at the right PSI. However I never actually know what is the "right" PSI. Looking at the tyres gives you a MAX pressure number. This can vary from brand to brand and sizes. However most tyre places seem to under inflate the tyres in my view. Like putting in 26PSI when the max is 44PSI. I never go the max, but I would go maybe 38 to 40.

Am I really supposed to go on the PSI listed inside the door, even though I don't have the same rims or tyres that came with the car?

I occurred to me that maybe all these years I've been putting in too much air. Now that I got some new tyres, I think I need to fess up and say, I'm just confused now if I've ever been doing things right.

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yup. 36 psi is about right for ~45 profile tyres in the sorts of widths we use. You'd be Ok running as low as 32 in a car that only commutes in traffic. For a fast hills blast you'd go up to 40.

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One of my current Bridgestones is showing wear in the middle of the tyre so maybe I've had it pumped up too much. I normally go 41PSI as I found out you'd lose 1PSI when disconnecting the hose. So was running in effect 40PSI in the rears, but now think due to that wear patch maybe it was too high. I do like them firm though.

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Wear in the middle is a good indicator it's overinflated (and that will vary between tyres and sidewall heights)

Higher pressures can carry more load, will use less fuel and will handle better. Downside is they can be harsher (but frankly, if you are running 45 or lower profile tyres you've already decided to accept a harsher ride).

In my experience tyre shops and mechanics tend to go for a low pressure (30 or lower) and I honestly don't have any idea why

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Maybe it's speed. Quicker to fill it up to a lower pressure and thus time is money sort of thing? I have no idea why they under inflate either, but I've always known they have for some reason.

These tyres were used when I got them, so not too sure it was all me with the higher pressure, but I think for this next set I'll go lower. Instead of 40 maybe start at 36/37 and see how that goes.

I like them high, but don't want to wreck the tyres.

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Wear in the middle is a good indicator it's overinflated (and that will vary between tyres and sidewall heights)

Higher pressures can carry more load, will use less fuel and will handle better. Downside is they can be harsher (but frankly, if you are running 45 or lower profile tyres you've already decided to accept a harsher ride).

In my experience tyre shops and mechanics tend to go for a low pressure (30 or lower) and I honestly don't have any idea why

...to get more grip perhaps?

It's probably not as extreme as with semis but I'm pretty sure that the same street tyre will grip better at 32psi than 42psi...?

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interesting idea, I'd love to see a back to back test. yes lower pressure will give you more rubber on the road but I'm not certain that translates directly to extra grip because each contact patch will move more relative to the wheel

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interesting idea, I'd love to see a back to back test. yes lower pressure will give you more rubber on the road but I'm not certain that translates directly to extra grip because each contact patch will move more relative to the wheel

Mythbusters proved it

http://actiontyres.worldsecuresystems.com/latest-news/effect-of-tyre-pressure-on-fuel-consumption

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FWIW I run 34 all around on 40 profile tyres, and at the moment have a really good alignment (for the first time in my life, i.e. no inner camber wear) and tyres are wearing evenly

No source, but I wasalways under the impression that higher pressure is better for fuel economy, lower pressure for grip, obviously to a point like so:

post-2-1196429733.jpg

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As usual, it's more complicated than it seems. 32psi is for putting around town with your family. I recommend 36psi for daily drivers, I run 38-40 depending on season/weather/tyre.

Cheap tyres generally need at least 40psi to get some grip out of it.

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I run 19's on low profiles and usually go 34 psi on the rears and 40 psi on the fronts. Find the ride sturdy but not too rough.

Hope this helps.

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My old mate a tyre guy and owner of his own tyre shop. I always bug him with questions which he doesn't like to give up his 40yrs experience......

Now he said not many people do it right dealership like soft gets a better sale softer ride.

Tyres say max.....

Door frame label says complete opposite.....

So on so on

Best is get a smooth flat ground dark as well. Now put some talcum powder on the ground in a line wide as ya finger but longer then ya tyre now push your car over the line keep rolling it 360 degrees so it makes a tyre print.

Now according to that print you would be able to tell if you need more or less you may need to do a few prints.

Remember front to rear will differ

Hope this help i might try make a video (if we have time ) with him helping me its a bit of an old art thats now days is forgotten.

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My old mate a tyre guy and owner of his own tyre shop. I always bug him with questions which he doesn't like to give up his 40yrs experience......

Now he said not many people do it right dealership like soft gets a better sale softer ride.

Tyres say max.....

Door frame label says complete opposite.....

So on so on

Best is get a smooth flat ground dark as well. Now put some talcum powder on the ground in a line wide as ya finger but longer then ya tyre now push your car over the line keep rolling it 360 degrees so it makes a tyre print.

Now according to that print you would be able to tell if you need more or less you may need to do a few prints.

Remember front to rear will differ

Hope this help i might try make a video (if we have time ) with him helping me its a bit of an old art thats now days is forgotten.

Sounds too damn complicated. How about you just tell us what you use on your tires? lol

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Unfortunately that would not work on your car unless you have a landcruiser with BFGs 265/65 r17 lol BTW dont own a skyline [emoji26] but i wish getting there.....

But yes all it takes is one person to do it then free 4 all

Example : R33 GT-R with Pirelli P Zero with this size ....______..... 36psi

Or with Proxes R888 size .._____.. 38psi

Its very rewarding at the end ;)

Edited by pol1on1
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