Checked tyres for first time this winter and had to put quite a bit of air into the front tyres. Now I've done this when I reverse with full lock on the front wheels seem to 'judder' and 'drag' themselves across the floor. Really strange. Its only happened since I changes the tyre pressure? According to the sticker on the car the front tyres require more psi than the rear about 34psi whereas the back are about 28. Is this correct too. Its an STI7 with standard 225/45/17's on.

 

That doesn't sound as though you check the pressures very often not weekly / fortnightly?

As for the dragging - are you sure it's the front wheels when reversing as full lock means you're trying to turn the car around on the rear wheels and because they don't steer, have to skid their way round to a certain extent...

Full lock is also the extreme of turning and you're used to driving and probably using small amounts of lock so don't notice the scraping whilst going forward - try applying full lock at 5mph (with a bit of space round you ) and see if you get the same effect...

34 / 28 psi - I can't comment on the actual pressures but it seems to be a large amount of difference between them - my WRX is only something like 1 or 2 psi higher on the fronts compared to the backs. The fronts are highr to cope with the mass of the engine and it's also the "steering end" so has to cope with more forces through the tyres.

Dunno what profile tryes you've been used to before but I think you'll find that lower profile ones are more sensitive to pressure changes - whether by temperature or if they've gone down over time. I feel I can tell the difference in the ride etc if they've fropped about 2psi (maybe it's bullsh*t but I notice the change blowing them back up to my preferred pressure level)

Apple

 

Could the 'dragging' have anything to do with the front diff??

 

or the judder could be knocking CV joints if on full lock