Importance of Tyre Pressure VS Load

cormie

Hi,
Does anyone know how important it is to follow the tyre pressure guides on a vehicle? There's usually two sets of figures given for front and back, one without a load and one with passengers/load. For a situation where half the time you're driving you've a full load and the other half an empty load, what's the best line to follow? I mean if I was to follow the guide, I'd be in the garage a few times a day so how important is it and if it's a case of always having varying loads, should you just stick to a figure in between the two, or just keep with the bigger load figure?

Any feedback appreciated

cormie

Thanks for the reply, yeah I have them all at the highest advised pressure and always have.

So really one of the only disadvantages of having higher pressure is the likelihood of oversteer?

.Longshanks.

cormie wrote: »

Thanks for the reply, yeah I have them all at the highest advised pressure and always have.

So really one of the only disadvantages of having higher pressure is the likelihood of oversteer?

Comfort and MPG comes into it too. But I'll let others explain that better

alias no.9

Tyre wear is also a factor, underinflated tyres will wear excessively on the outside edges, overinflated will wear excessively in the middle. If your tyres sho no obvious signs of doing this, then everything else is probably ok as your getting good contact between the tyres and the road.

woody33

Lots of info here:


http://www.carbibles.com/tyre_bible_pg3.html

jadatis

There is a formula that the European Tire- manufacturers use to determine the pressures.
I once got hold of that and worked it out .
Learned myself Excell to make spreadsheets for it .
translated a few to Englisch to go worldwide with it ( from Dutch).

Important for the pressure is the load on the tire and the speed you ride.
Also for race cars the camber-angle if above 2 degrees.
Placed this all in a spreadsheet for re-calculating when other then original tires, but can also be used for checking the original and see if you can go lower in sertain conditions.
http://cid-a526e0eee092e6dc.skydrive.live.com/browse.aspx/.Public/Recalculating%20tyre-pressure
in this map the spreadsheet with examples.
I think this will answer your questions, let me know.

You can also fill in your own input , if you weighed the axles or better the seperate wheels . Then take twice the heaviest side per axle, and you can use my own input , the load-percentage( LP).
It means that if you calculate the pressure for say 1000kg, and the real weight on the tire is 850kg , the load-percentage is 85%
You may not use LP more then 100% , it might damage the tires.
100% gives the best grip .
95%LP gives the longest live of the tire.
100% and 90% gives about 95% tire live.
the lower the LP the less fuel consumption.
I concluded myself by reactions that under 85% people experiënce discomfort by bouncing, and under 80% screws come loose from caravans.
So the best loadpercentage to calculate with is to my opinion 90%, a good anaugh grip and a save margin and neat fuel consumption without discomfort.
You can fill in at "your own input" = 900/0.9 and then enter to get 1000, but then with your own weight with the LP you want .
The lower the LP the lesser gripp ,so you can influence over or under stear, by using lower LP on the axle you want to slide first.

cormie

Thanks for the info everyone