Tyre pressure indicator

[ultra]

My tyre pressure indicator went off on the weekend while driving , alerting me that one of the tyres was going flat which was great, Pulled into the closest servo to check the tyre pressure and low and behold the rear left showed it had 25psi , What i am wondering is, what is the standerd tyre pressure on the 18" wheels ? cause as i checked the tyres i noticed that the
front right had 41 psi, the front left had 42 psi and the rear right had 40psi. so i looked all over the car to see what the standerd tyre pressure loads are and found it in the petrol cap/ flap but could not understand how to read it. I ended up inflating the fronts to 42 psi and the rear to 40 psi . would anyone know if thats correct ..

[pirelli]

check this topic i am sure you find the answer here

http://www.vwwatercooled.org.au/newforum/upload/showthread.php?t=29669

[Arctra]

Hey Ultra, glad to know the tech saved you and your tyre.

As far as tyre pressures go, as I put in the care sheet, the rule of thumb (that I use anyway) is tyre manufacturers max pressure as displayed on the tyres sidewall less 10% of that max pressure. So my tyres have a max pressure of 40psi so I pump the fronts to 36psi (40 less 10% of 40).

I did some testing this weekend though, and came to the conclusion that in my Tig, with the boot emply and a full tank of fuel, I need to have the back tyres 2psi lower in order to have approximately the same contact patch. So I run 36psi on the front and 34psi on the back. But I have 215/65R16's on my Tig, you'll have to play around to figure out what you need to do on yours.

[ultra]

thanks for that guys will look at it first thing when i get home..

[ultra]

ok this is what i found , 18" wheels max psi is 51psi subtract 10% you get 45.9psi. So we are looking at the fronts at 45 psi and rear at 43 psi.

[Bora Sport]

The first thing that I would be checking is why that tyre pressure was so low in the first place.

[ultra]

Ive had a good look around the tyre and could not find anything noticable. But now that has happened i will be checking the psi of that tyre everyday to see if it is still leaking and if so will have to get it repaired..to be so low there has to be something but can't jump to any conclusions yet..

[MGV]

Pressure & temp queries...

After a pressure check on a chilly morning, i began to wonder what sort of difference i should expect between hot (been driving), ambient (normal/average temps before driving) & COLD... (about 8 degrees when checked before a drive yesterday)?
The reason i ask is that i normally run 36psi all round, but when checked (with my own 'good' guage i keep in the glovebox) yesterday (chilly) i had a readings of only 30-31 all round!
So i did a bit of a search, found this thread, went out to the garage & read the max pressure for my tyres is 50psi & if applying the above philosophy, i should be inflating to mid 40's... Does that sound about right? Rolling on 19's, 245/40 Bridgestones.

Thanks in advance for thoughts, scientists!

[Tiggy1]

Hi. New to these, so could be wrong. Tyre pressure placard inside fuel filler lid says 2.2 bar, which I convert to 32psi. Seems low I know, but that's pretty much what was in the tyres. Wouldn't want any more in there as ride is already pretty firm (certainly not squishy). Maybe less than normal because are 18" with 235/35 tyres?!

[NZTiguan]

Hi. New to these, so could be wrong. Tyre pressure placard inside fuel filler lid says 2.2 bar, which I convert to 32psi. Seems low I know, but that's pretty much what was in the tyres. Wouldn't want any more in there as ride is already pretty firm (certainly not squishy). Maybe less than normal because are 18" with 235/35 tyres?!

Would have to say that in my personal opinion I'd be looking at what the manufacturer of the vehicle recommends rather than taking any notice of the max pressure given by the tyre manufacturer. I would say that 32psi on 18s would be about right. My specifications from the sticker on the fuel flap are 32psi all round with 2 people and 36 front 39 rear fully loaded, and I run 34 all round for convenience.

Cheers

[Corey_R]

I disagree NZTiguan.
The tyre manufactures "max pressure" should ALWAYS override what the vehicle manufacturer says. What does Volkswagen know about Tyre Company A's Model B tyre's composition? Probably nothing.

The "max pressure" is just that. The max, and you should NEVER exceed that.
Thankfully, most tyre's max pressure is always more than what the tyre placard from the vehicle manufacturer recommens anyway. So in that regard, yes, follow the placard in the fuel flap.

Just always take the tyre manufacturers "mins and maxes" as overriding factors to what the vehicle manufacturer says

[NZTiguan]

I disagree NZTiguan.
The tyre manufactures "max pressure" should ALWAYS override what the vehicle manufacturer says. What does Volkswagen know about Tyre Company A's Model B tyre's composition? Probably nothing.

The "max pressure" is just that. The max, and you should NEVER exceed that.
Thankfully, most tyre's max pressure is always more than what the tyre placard from the vehicle manufacturer recommens anyway. So in that regard, yes, follow the placard in the fuel flap.

Just always take the tyre manufacturers "mins and maxes" as overriding factors to what the vehicle manufacturer says

I certainly agree that you shouldn't exceed the tyre manufacturers max limits and I never suggested you should BUT I also don't think using those limits and subtracting a percentage to give you your tyre pressures is what you should do !! That's what I was saying, not that you should ignore what the tyre manufacturer states. Mind you, personally I've NEVER even looked at the max allowable pressure on my tyres except for my wheelbarrow !!!

[Corey_R]

Yeah, agreed

[brad]

My way of fine tuning tyre pressures is to start with the tyre placard recomendations & recheck after 30-45mins of driving in your "regular style" with your "regular load". If pressure increase is more than 10% of what you started at then the starting pressure is too low. Add 2-4psi & repeat the next day (because you have to start with cold tyres).

Generally the manufacturers recomended plus another 2-4psi works for me.

32psi in 18s? Seems a fraction low. Sure the ride might be comfortable but the tyres aren't there to be a suspension component. If you want to avoid impact damage to the sidewalls & flat spots on the rims, I'd run 34-36psi as a minimum.

[Tiggy1]

Hi mate. I know what you're saying - I used to run 34-36PSI in my Forester, but it had much higher profile (215/70 R17). I feel the extra sidewal height DOES make a difference (especially on our S*&t roads). Have read & seen many car reviews that agree. Bump absorption is very good, but ride noticeably harsher than Foz. Will try bumping them up to 34PSI and see how it goes (when I can find decent tyre guage - had cheapass SCA one, but it died)
Cheers