Hi Guy, if I was using 'fresh' 40 plus year old technology tyres on a
Healey, those factory manual settings would have been appropriate.
Forget the manual, it's almost 2010. Your loaded run pressures are
much closer on a spridget than the factory manual.
The "max inflation pressure" guideline on the sidewall is a good
general target to aim for hot. Usually around 37 - 40 psi hot. Usually
30 - 36 psi cold. As a rule of thumb. General guidance. No warranty
implied or offered......
Ambient air temp affects this too. I'm basing my experience on living
in Sydney, Australia, where we just don't experience the temperature
variations in a year some of you guys do. But the again, if it's
snowing, you probably aren't driving the Healey at 10 tenths anyway,
are you? I'm talking summer/ nice Healey driving weather.
;-)
Chris
Sent from my iPhone
On 17/12/2009, at 12:44 AM, "Guy R Day" <grday@btinternet.com> wrote:
> As no-one has come up with definitive tyre pressures - the MG Midget
> Mk III 1967 handbook says:-
> Wheel size: disc 3.5Dx13; wire 4Jxl3 5.20x13
> Tyre size and type Dunlop C41 Gold Seal (Nylon) Tubeless 5.20x13
>
> SP 41 - Tubed Radial (still a stiffish
> one)
>
> Tyre pressures (set cold):
>
> Normal . . . . Heavy duty . . . . SP41
>
> Front . . . . . 19 psi . . . . . . 22 psi
>
> Rear . . . . . 20 psi . . . . . . 24psi
>
> For sustained speed in excess of 80-85mph
> Front . . . . . 22 psi . . . . . . 22 psi
>
> Rear . . . . . 24 psi . . . . . . 24psi
>
> Haynes Workshop Manual states:
>
> Crossply . . . . . . Front . . . . . . . Rear
>
> Normal driving . 18psi 20psi
>
> Max load . . . . . 18psi 24psi
>
> High Speed . . . . 22psi 28psi
>
> Radial . . . . . . . . . Front . . . . . . . Rear
>
> Normal driving . 22psi 24psi
>
> Max load . . . . . 22psi 26psi
>
> High Speed . . . . 28psi 30psi
>
> Mine ran normally at 28front / 30rear, upping to 30f/30r for a
> lightweight fast run and 32f/34r for a loaded run.
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