Changing tyre size - wider/lower

[prvoke]

Since im new to bikes im not sure what you can do with one up one down sorta thing like you can with cars. I have a CBR250R with a 100/80/17 front and a 130/70/17 rear. Can i go to say a 110/70 F and 140/70 or 140/60 R?
IS there any advantage to doing this? Just havent seen a lot of 100/80s in my short time looking at what new tyres to buy. I have Bridgestone Battleax BT45s front and rear, the front one is pretty shot and i figured i may as well do a matching set ?
any help is appreciated

[FROSTY:Me]

Those lil bikes wont like upsizing.The bike will steer slower and be harder to put into corners.

[Grub]

Someone very wise pointed out that the Honda R&D team (they spend 10% of revenue on R&D) probably tried all the combinations before they put the bikes into production.

They tried all the tyres, all the wheel sizes and all the combinations thereof. Then they wrote the spec on the best wheel/tyre combo for those bikes. As Frosty says, people who have thought they knew different have ended up with bikes that are pigs to ride.

Sure big fat tyres look cool but they stop you tipping into corners and probably rub on the swing arm. The guy I bought my first CBR600 off went back to the book when it needed tyres and that was (still is) the sweetest handling bike of all. Even the local Kawasaki dealer siad so ... and used half a tank of my gas trying to disprove it

p.s. If your bike is an '89 then it will most likely have crossply tyres - don't even swap them for radials, the bike wasn't set up for them.

[prvoke]

i did some research on CBR250.com and they all reccomend going to 110/70 F and 140/70 R. some say you can go to a 150/60 R but it affects the handling so i think il just go with what they reccomend. now i jst gotta choose brand/model

[Animal]

I agree with Frosty and Grub's comments. I found going to wider tyres on a similar sized bike made it look a bit more serious but didn't do that much in improving the handling. I then went back to the stock tyre size but spent up on the best quality tyres available. That made a significant difference!