TammyN
Wore out three sets of tires already!
I'd be nervous about using oxalic acid or anything acidic on red, brown or orange paint that's weathered or is fragile. Those colors usually have red oxide pigment, which is iron(II)oxide. Rust is a form of iron(II)oxide so it seems like anything that chelates or sequesters rust could do the same with exposed paint pigment. That might be what happened to the part in the photo that turned pink-ish.