Sounds like for a start I may want to try a few more PSI in the Avons.
I noticed that this one seems to contact the tire, where the one you recommended
https://tinyurl.com/toe-gauge uses a scribed like which seems far superior? I guess you have to jack up each wheel, spin and chalk before measuring, not a big deal.
Bluesman,
Planenut is correct you should verify the wheel/tire for trueness before embarking on any form of measurement. Any sort of scribe can work: chalk, Sharpie, even a screwdriver blade to make a viewable mark. Once I'm satisfied the tires are centered on the rim (i.e. the tread pattern isn't wobbling about-which is pretty rare) I no longer bother with the scribe and just measure off of the tread blocks themselves.
As for the cheaper one you found online, I did borrow one of those some year ago. The issue I found with indexing off of the tire sidewall is that raised lettering or any sort of sidewall embossed feature will affect the readings unless you can ensure contact front and rear with only a smooth part of the sidewall. And that design doesn't lend itself to indexing off the rim without modification. I politely returned it to it's owner and bought the one I use today.
Kankel's suggestion for toe plates is very valid as well, especially with our tall skinny tires.
As I do rebuilds and suspension setup on many types of cars I have found the pointer type that I use is the most versatile, allowing me to measure/set toe even without wheels present.
