Originally posted by CraigCline:
... Why do the new wheels need so much more positive offset (added back spacing) compared to my old wheels ...
Good question Craig. As a generalization most aftermarket Pantera wheels are built with too much front offset and too little rear offset. The front wheels are 8 to 9 inches wide and have 22mm to 25mm offset. A 245mm tire rubs the inner wheel house, and looks excessively recessed. By contrast the rear tires are generally offset to be flush with the fender edge; in fact the 335/35R17 tires stick-out from the fender by 5mm! Then the level ride of the chassis is upset because the rear tires are generally much smaller than OEM, so the rear end must be jacked-up or the front end lowered. You end up with a front tire that fills the fender arch as intended, but a rear tire that has a big gap between it and the fender arch. So the appearance of the tires is imbalanced front to rear in two ways, the amount they are recessed by offset, and by the gap between the tires and the fender arches. On top of that, the front tires are not centered within the fender arches, they are shoved forward. Correcting these things has been a crusade of mine.
Yes small diameter tires and the vehicle's ride height both impact tire clearance. I recommend 6mm offset for 225mm front tires, and 16mm offset for 245mm front tires.
I have a wheel width and offset guide I'll attach below.
Originally posted by Garvino:
... Let me know if I can be of any further assistance ...
Devin thanks again. You've been a great help. Very cool that you are helping the school with the kids.
I agree with you regarding the appearance of a "small" amount of tire recess. Emphasis on the word small (20mm?). Its also a very practical choice. I'm also excited that you were seeking the same recess front and rear, something I've been harping about for a long time. Finally I'm happy to see somebody "buck" the trend and use something less that 22mm to 25mm front offset.
#6018 has been my guinea pig, and it seems there is some variation between our Panteras. The 325mm rear tires previously installed on 6018, mounted on wheels with 12mm offset, were flush with the top of the fender lip, not recessed. I wonder if that might be due to the tires themselves, as I used Michelins PS2's, and they were very wide. Whatever the explanation, it is a lesson for everyone to keep in mind.
Finally I'd like to comment about the Pantera's front caster. If you take a look at any Pantera in which Ford reduced caster to about 3 degrees, you'll notice immediately that the front tires are not centered in the fender opening, they are pushed forward. This resulted when Ford moved the upper front ball joints forward about 1/2 inch in order to cut caster in half.
If an owner moves the upper front ball joints rearward 1/2 inch in order to increase caster, restoring it in the range of 5 to 6 degrees, it centers the tires in the fender openings AND looks much better. There shall be no increases in rubbing in as much as the tires are positioned (centered) in the wheel wells as they had been originally intended. If there's any tire rubbing it will be on the inner wheel house, and only with the widest 245mm tires, because the vendors insist upon 22mm to 25mm offset. And even then its only during full lock parking lot maneuvers, nothing dramatic.
Besides appearance the increase in caster improves forward stability, and what is less understood is that cornering "bite" improves as well, because the front tires "lean" into corners more. Ford reduced caster to reduce "bite" and increase understeer. Ford "dumbed down" the Pantera chassis in this way because they believed their customers could not cope with the full capabilities of the chassis (i.e. the immediate response to driver input).
In terms of chassis response to driver input I personally want more! That's why I am a sports car enthusiast. Therefore from my perspective Ford's decision made no sense at all back then ... nor to this day. I don't want to revise the Pantera chassis to make it something better than it was intended to be, but whatever capabilities it was intended to have, I want them all ... undiluted by corporate Ford's committee made decisions.
Craig here's the wheel width and offset guide.