Hi guys, So many of you have recommended the Maxxis tires for our WR450's... i would like to try them. However I am a little confused. I've been though many sets of tires on my R1 and there was alot to learn with street bike tires. This is my first dirtbike tire purchase i am not sure about the correct part#'s. FRONT: Front Size: 80/100-21 51M Maxxis Maxx Cross Soft/Intermediate Terrain - This is the SI tire right? Should i use the original size? 80/100x21 Maxxis Maxx Cross Soft/Intermediate Terrain Our price: $49.99 Part# 77528 Rocky Mountain FRONT REAR: Rear Size: 110/100-18 64M Maxxis Maxx Cross Intermediate Terrain - This is the IT tire right? Should I use the original size for the rear too? 110/100x18 Maxxis Maxx Cross Intermediate Terrain Our price: $44.99 Part# 77975 Rocky Mountain REAR Also, why is the rear cheaper than the front? And has anyone found these anyplace cheaper? Some of the websites that have Maxxis dont have the SI front... is it an older model?