I rode a 450R today with a Dr. D pipe and really dug the power. However, the front end comes up way to easy for my liking, I have heard extending the swing-arm is a good idea for MX and to keep the front end more grounded. What effect does putting smaller tires on a 400EX or 450R?

 

the smaller the front tires are the more difficult it will be the pull wheelies

 

Handlebars that aren't as tall, will make a difference also. On most bikes, I prefer bars that are usually lower than stock. I put TAG T2's on all my performance bikes, and it makes them less likely to wheelie when you don't want them to.

Smaller tires will make a machines steering faster, and more twitchy. Not a good trade-off, in my opinion.

 

the smaller front tires, along with stock 2 ply tires make the bike wheelie easy. extending the swingarm on a 400ex 1.25 inches really really makes it tough to ride a wheelie. i currently run 21's and this extended swingarm on my 400ex. the tires seem to have less sidewall so they are a bit bumpy. looks cool i guess. i mainly did this because i like dragging and i needed to loose some weight on the bike. it is much harder to get traction with the extended swingarm though.