[DeTomaso] 245/40/17 Front Tires
jderyke at aol.com
jderyke at aol.com
Thu Dec 24 14:02:46 EST 2009
The limiting factors on front tires have been described many times but
perhaps not comprehensively; this is what I've found to be true on a '72-1/2
L-model with no flair mods:
max. 24" OD at the tread
max.10-3/4" section width (fattest part of the tire carcass)
max. 9-3/4" tread width
On 8-9" wide wheels with 4-7/8" to 5" backspace, regardless of wheel ODs
from 14-19".
Notes- does not address clearances for non stock brake rotors nor handling
improvements.
Unmounted tires have slightly different measurements than mounted, properly
inflated tires.
Brand X's 245-40s may be wider or narrower than Brand Y's 245-40s; tire
OD's and section widths are not tightly standardized by tire mfgrs.
Repaired crash damage (expert or not) can radically alter all or some of
the above.
Max-sized front tires WILL ALWAYS need some mods to stock inner fenders and
ajacent parts, or modified flairs on the outer fenders, or raised ride
heights. ALL performance driving will require rolling the fender lips- even with
stock 185-70x 15" tires, as the factory found in 1973.
Other factors that affect max. front tire size on U.S-imported cars are:
whether the stock headlight-height spring spacers are in or out,
whether the car has non-stock road height from changes to shock length,
shorter springs or non-stock alignment settings,
whether you routinely make lock-to-lock turns at higher speeds
whether you absolutely do not want any rubbing at all,
whether you carry passengers and lots of stuff in the front trunk,
whether you drive hard or only want big tires for appearance, and so on.
There's a more extensive write up of all known front end parameters on
undamaged Panteras in the Jan '10 POCA Newsletter (now in the U.S Mail). Merry
Christmas- J Deryke
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