I have a cbr 600 FX/Y (uk version of the F4) and the tyres I currently run are Metzlers 160/60/17 and 120/60/17 but a stats say I should be running 120/70/17 and 180/55/17 (looking ar getting bridgestone BT023) what's the problem with running non stock tyre sizes? And would you recommend going back to a stock size?

 

Mmm, I have the same year bike, the 1999 FX mate, and what's happened there is, previous owner being a numpty has put F3 tyres on it... which were 160's... you need to get 180's on mate. Safety, probably not a problem... BUT the bike was designed and weighted to run 180's... also there could be the fact that the alloy is wider on the F4 (???? can anyone confirm this, I'd assume it is) so take the 180. Bear in mind, that's 2cm difference... you sure you've got FX/F4 alloys mate? as to me with a 160 on there, you'd not be able to run 160's, they'd simply not fit width wise? Which means if you're running F3 alloys you won't be able to put F4 width tyres on I would've thought...

The profile of the front being a 120/60 won't really matter as much as that's just means the front is a lower profile... however I'd get that back changed ASAP, it'll handle sweeter so they reckon. I've just replaced both my tyres for £139... Pirelli Diablo Strada (yes an older tyre but got good reviews so)... 120/70/17 and a 180/55/17 all for £144 inc postage and packing!!!

EDIT. Show us a piccy of your bike matey :-) I love piccies :-0

 

hmm.. post pics of the rims. as pug said, if you are running different rims, then you will have to match to those rims. but if you have f4 rims, then you should go with stock tire size. i wouldnt think it would hurt going to a higher or lower profile would hurt anything other than your speedo accuracy, but you always want to stick with the right width no matter what. if you still have stocks wheels, then im guessing that maybe a previous owner just threw on what they could get their hands on for a nice discount price..?

 

Yep, those are incorrect sizes. OEM is 120/70 & 180/55. Change 'em & sell the others to an SV650 owner.

 

Sorted the issue I was looking at the f4 not the fy lol

 

>??? F4/FX/FY all the same bike?