A few of my personal thoughts on tire and wheel sizes FOR THE STREET; all have been tested by myself and my wife over 39 yrs of ownership with no crashes.
If you're attempting to maximize tread width and cornering, 225-50 x 15" fronts on 8" wide Campys seem a bit stretched. I don't use the 7" Campy version, I use 245-50x 15"s- about the widest front tread size one can run on an unflared Pantera body regardless of wheel diameter. Even then, some minor hammer-contouring must be done on the inner fender panels and fender lips rolled, for clearance in tight turns. More so if the U.S DOT bumper-height/headlight height spring spacers are removed and extra caster added. 8" Campy front wheels also correct the poor scrub-radius produced by 7" Campys. I suspect Dallara's first recommendation for the Pantera was for 8" fronts.... or else the excellent fit is pleasantly coincidental.
The first instance of 10" x 15" 'DeTomaso' Campy 5-window wheels were on the Euro Pantera GTS/Gr-3, noted in the 1972 GTS/Gr-3 Supplemental Pantera Parts Catalogue. Along with those wheels were listed 225-50 x15" P-7 front tires and 285-50x 15" P-7 rear tires. The rears were about the widest street tires available at the time and were used in club-racing & hill-climbs. 295-50 street sizes were not yet available or go-fasters would have snapped them up! GR-4 and GT-4 racers, of course used even wider slick 'gumball' racing tires with relocated a-arm points and flares.
The 245-50 front/295-50 rear tire combination works well on the street on our '72, but to maximize big tire benefits, I use stock OD HOLLOW front antisway bars and HOLLOW 1" OD rear antisway bars. Hollow bars cold-bent of thickwall 4130 tubing are slightly less stiff than replacement solid bars of the same OD. The softer hollow-bar action works well with an otherwise stock Pantera chassis and drops about 50% of the unsprung weight of the bars. I also found it necessary to add Koni adjustable shocks front & rear with different springs (available in the '72 Gr-3 catalogue).
All this, along with all-custom alignment specs, a 2 degree nose-down attitude and a minimal Peter Revson front spoiler (the Gr-3 catalogue lists an equivalent front blade spoiler but I like Revson's curvy design), allows us to take full advantage of the remarkable handling and high speed stability Dallara gave the Pantera. Above 170 mph, a blade rear spoiler (or wing) might be needed for added anti-lift, according to regular SS runners. And if you're running way up there on the speedo on the street, you don't need MY suggestions! You may need a Viet Nam era 'get-out-of-jail-free' card, though...YMMV.
J DeRyke