Correct Tyre Pressure

xzanti

I'm sure this has been asked before but a quick search brought nothing useful up.

I'm wondering if I have my tyres at the right pressure? I have them between 29 and 30, which I was told is correct but they just don't look very 'full' for want of a better word, and I'm worried this is having an impact on my fuel consumption..

Cheers

Alun

Why not just check the sticker that all cars have somewhere that tells you what pressures to use? Could be behind the filler cap, on the door sill, or on the inside of a door pillar or just look in the handbook (if you have one).

Henry Ford III

Correct tyre pressures vary car to car. Consult the handbook.

xzanti

Handbook... D'OH

cheers

Viper_JB

On allot of cars it'll be on a label under the drivers door

Mr.David

Whats the car?

woody33

But then the correct tyre pressure in the book refers to cold tyres, and of course the tyre are warm when you get to the garage. Some people like to keep their tyre a few psi above the suggested figures and claim better economy, a firmer ride and better roadholding, but that would be at your own risk, and VW for instance recommend higher pressure for full load or high speed. I have seen pictures of a tyre at correct pressure and then at 10 psi under, and you can't tell the difference just by looking.

Justin10

I have 15 inch wolfrace alloys on my car. Buy sticker is for 13 inch.
I put them at 29 but they look empty like the OP said. Can anyone tell me what they should be?

TheColl

woody33 wrote: »

But then the correct tyre pressure in the book refers to cold tyres, and of course the tyre are warm when you get to the garage. Some people like to keep their tyre a few psi above the suggested figures and claim better economy, a firmer ride and better roadholding, but that would be at your own risk, and VW for instance recommend higher pressure for full load or high speed. I have seen pictures of a tyre at correct pressure and then at 10 psi under, and you can't tell the difference just by looking.

My book gives me the tyre pressure for warm and cold tyres. And yes it too recommends higher pressure for full load, makes sense really!

SV

Rochey18 wrote: »

I have 15 inch wolfrace alloys on my car. Buy sticker is for 13 inch.
I put them at 29 but they look empty like the OP said. Can anyone tell me what they should be?

try 33 ish.

corktina

its not an absolute...so long as they arent flat and are the same each side of the axle they are probably Ok...add a couple of pounds if you think they are too flat, but low profile tyres often look that way

jadatis

I kept myself busy with calculating tyre-pressure with use of the formula the European car- and tyre-manufacturers use to determine the advice pressures on the stikker somewhere on the car.
Learned myself Excell to make spreadsheets for it.
Translated a few to Englisch to go worldwide with it, becauce my opinion is that if you chanche the specifications of the tyres, the tyre-specialist does not give a acurate answer, because he( or she, its 2010) does not know how to re-calculate it.
Now I am Googling for Tyre-pressure to see if I can shorcut discussions about it .

http://cid-a526e0eee092e6dc.skydrive.live.com/browse.aspx/.Public/Recalculating%20tyre-pressure
In this map on my sky drive of hotmail the spreadsheet and examples to re-calculate when other then original sises of the tyres.
Yust use it and ask me here if there are questions about it.

http://cid-a526e0eee092e6dc.skydrive.live.com/self.aspx/.Public/pressurecalculationwithtemp.xls
this older spreadsheet is meanth to see what the inside-tyre-temperature does to the pressure. The first part calculates the pressure for up to 160km/99miles/h. and I introduce the load-percentage there.
My idea is, based on reactions, that if you take care that the real weight on the tyre is between 85% and 100% of the load the pressure is calculated for , you have a smooth ride with no chanche of tyre-damage.

The European formula is up to now the savest one, beter then the older American one , wich is chached slowly richt now to the European one ( coincidently after the Ford/ Firestone afaire?
found also an article about tire-pressure at reduced loads, in wich a new formula
http://cid-a526e0eee092e6dc.skydrive.live.com/self.aspx/.Public/tirepressureatreducedloads.pdf
Endconclusion is that with bigger tires and higher pressures the European formula gives still to low pressures.

GTE

Forgive my ignorance, but why not pump it to nearish the max PSI stamped on the tyre?

jadatis

Because then, if the load on the tyre is much lower then the maximum of the tyre, the fillings come out of your teeth. And also you will have less gripp on the road .
You can also use the loadpercentage I mentioned to influence under-and over-steer .
If you pumt the rear harder and the front as calculated you create oversteer and the other way around for under-steer.

Esel

bbk wrote: »

Forgive my ignorance, but why not pump it to nearish the max PSI stamped on the tyre?

Sorry, no can do. That's a doozy, tbh.