General 500R tyre pressures

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General 500R tyre pressures

lazylobster

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Hi all, as per the title.

Running standard 125 tyres on 3.5 wheels. Whats the PSI required please?

Got the slightly heavier 595cc lump in it etc.

Thanks
Rob
 
According to the 'Factory' workshop manual, tyre pressures for the standard 500 are:---(light) Front--17.1psi (1,2kg/cm)---rear--23psi (1.6kg/cm) and (full load)--front--17.1psi (1.2kg.c)---rear--26.3psi (1.85kg/cm). The Mk1 '126, which has slightly bigger wheels recommends the same for the front, but 28psi (1.97kg/cm) for the rear. The 126 is a bit heavier than the 500. My suggestion in the light of these figures is to leave the front 'as is' (21psi) and increase the rear by just 2psl.
 
From experience on standard tyres with the slightly heavier loading of the 650 engine, I agree that you go midway on the Fiat advice on the rear...ie. 25psi. As these pressures are pretty low I find that standard gauges fitted at service station pumps, on inflators or even the dedicated hand-held devices, can give very inaccurate readings. The handling of the car is badly upset when the pressures are wrong, so I opted for a fairly expensive, analogue gauge as supplied by Transair, which is an aviation supplies company.
 
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