My understanding of tire pressures always has been that factories tended
to recommend those low settings in front as a *safety* measure. I'd have
to disagree with Jerry; lower tire pressure usually means LESS stick, and
understeering conditions are more desirable for the *average* driver than
are oversteer conditions.
I don't know if this applies or not, but: back in the earlier stages of
radial tire development, steel-belted radials -- such as Michelins --
tended to break away more suddenly at the limit than did fabric radials
such as Pirelli Cinturatos. Perhaps the lower front pressure
recommendation was an attempt to help compensate somewhat for that.
It's all somewhat academic now, as tire technology has progressed quite a
bit since the 1960s. Personally, I think 17 in front is far too low
nowadays; I'm sure handling would be much improved on a TR with higher
front pressures than that. 26-30 all 'round probably is good for
many/most drivers and situations; maybe a little less in front, but not
8lb. difference! YMMV, of course!
And, yeah, bias tires: I had a TR3A in the early 1970s on a matched set
of Dunlop Gold Seal 6.85x15 bias ply tires. Fine on dry, smooth pavement,
but on water, gravel or ice, or in any sort of power-on condition...ARRGH!
--Andy Mace
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