Help! Rear Tires sizes ??

[Crooz]

What is the most popular rear tire size upgrade (thats wider than stock).
Just how big (wide) will fit?

[jtenright]

I have 140/70
but many ppl have 150/70, which is the biggest our rims will take

[TheGoodGuy]

BT45 Spec H 140x70x17 Rear
and 110x70x17

Check with cyclegear, they quoted me 180 for both.

Discountmotorcycletire.com is 170 with shipping.

[pantablo]

Hard to say which is most popular.

The 140/70 is fairly common upgrade as is the BT45. Good combination overall.

Some have gone to 140/80 seeing as how the radials are only available in this combo. Taller means flicks easier and also adds about 1" to ride height.

I've seen 150/70 installed and its a tight fit-so tight that depending on the manufacturer it may or may not rub the chain and brake stay arm.

I've got 150/60 and its the smallest tire good rubber is available in (talking US only). Michelin Pilot Sport.

Note that the 150 tires are not (mostly) approved for our narrow rims and because of that the tire gets pinched. Means you have slightly less contact patch on ground esp when vertical (not turning) and the edges are unaccessible.  You can go to the trouble of upgrading the rear rim if you're so inclined (as I am) to get proper fitment of the 150 (or 160 possibly) but be warned that even these sizes look small when you pull up to the bike night and everyone's wearing 180's.

BT45 in 140/70 is your best bet.