Over inflated tires?

bainbridge · 9 Sep 2011 at 20:57

Johnnytoxic said:
My front wheels are suppose to be 35psi. If i put them to 40psi, would my fuel economy improve ?

Yes, less rolling resistance = higher speed, I've pumped all 4 of mine up to the 40psi max limit stated on the actual tire & a full tank does go noticeably further, with the cost of fuel nowadays I think this is worthwhile when weighed up against increased wear & tear on tyres & suspension.

dalin80 · 9 Sep 2011 at 21:07

Its probably for the best that most of you dont know what pressures are often required to fit tyres (especially low profile) to a rim.

On another note, tyre compliance is taken into account with suspension geometery and over inflated tyres can exaggerate suspension settings such as caster meaning your car can feel like its pulling with the road more then usual. Also less give in the tyre can cause negative camber settings to wear the edges of the tyre which is often mistaken for the track being out.

Gaygle · 9 Sep 2011 at 22:02

bainbridge said:
Yes, less rolling resistance = higher speed, I've pumped all 4 of mine up to the 40psi max limit stated on the actual tire

Are you sure that 40psi is the max limit or 40psi is the max for beading the tyre.

Frozennova · 9 Sep 2011 at 22:07

Gaygle said:
Are you sure that 40psi is the max limit or 40psi is the max for beading the tyre.

Most tyres I recall looking at are around 50psi+ max pressure so I'm assuming thats probably beading pressure, although a mate thats a tyre fitter had one bead at 70psi while I was there the other day.

Fuzz · 9 Sep 2011 at 22:14

dalin80 said:
Its probably for the best that most of you dont know what pressures are often required to fit tyres (especially low profile) to a rim.

ahh the joys of tyre machines "safety inflater".

I've run away from a few after putting all the normal infllator will give it and it still hasn't beaded. :eek:

Dr Who · 9 Sep 2011 at 22:25

Scubascorpion said:
ahh the joys of tyre machines "safety inflater".

I've run away from a few after putting all the normal infllator will give it and it still hasn't beaded.

Beading used to scare me as well

Dogbreath · 10 Sep 2011 at 10:50

Nick1881 said:
You will notice BMW also recommend higher pressure in the rear (4-5 psi more)

High pressure compared to what?

Nick1881 said:
this is to increase rear grip, their reasoning is your average driver will be able to correct under steer easier than over steer.

High pressures do not normally provide more grip, though it initially feels like it does as the slip angle reduces.

mattyfez · 10 Sep 2011 at 11:41

It's an interesting subject, the guidelines for my car are 29psi front, 30psi rear normally, and 38psi all round if fully loaded with people and luggage.

I generally run at about 33psi front and 35psi rear, seems to feel better.