Usually run 2.1 both F&R.

How much difference in head angle/handling would running a 2.3F and 2.1R make? Noticeable or negotiable? What would be the equivalent reduction in travel if I were to correct it with a u-turn fork?

you could turn your fork down by .2″

difference in head angle will be less than a quarter of a degree otherwise.

Going for a carp before getting on the bike would probably have more of an affect.

Al knows. He’s a maths boffin.

Assuming each tyre has got a 100% aspect ratio, that’s 0.2″ on the diameter, or 0.1″ on the radius.
That’s less than the tread depth.
Do you notice a change in the head angle as your tyres wear down ?

radius, not diameter.

and given his tyres year equally how would that change the geometry?

ooh…bottom bracket height! 😀

Aha, but what happens as his camel back drains?

and given his tyres year equally

But rear tyres wear a lot quicker than fronts.

Cause we all secretly love a nice skid every now and again. 😆

and when he goes for a pi$$ 🙂

stu you have not accounted for the higher pressure in his rear tyre 😎

😆

I said radius. 😕

Anyway, there seems to be more than 0.1″ radial run out on the average mountain bike tyre from what I’ve seen.
That means the frame geometry must be changing with every revolution of the wheels.
In fact, the change would constantly vary during a ride depending on whether the high and low spots on the two wheels were synchronised or not.
It’s a wonder anyone ever manages to ride a bike.