My Mrs has a 250r. and I know which vid you've seen that say a 150 will fit. IT DOESN'T. the widest you'll get is a 140, the standard 130 rubber on the 250r is absolute rubbish. it's the first thing you should bin when you get your bike..you'll be amazed at the difference. the second thing, bin the heavy exhaust, I found a Two Brothers system on ebay, and it sounds NAUGHTY..(check utube-250r two brothers..oooh!)...next she wants is a change in suspension, but at £850 + for an ohlins system, she'll have to wait.
(just found this on another site: Front tire: Pirelli Supercorsa SC1 (110)
Rear tire: Pirelli Rosso II (140)
(there's alot you can do with them, because in countries like Indonesia, any bike above 250cc, gets a wopping 200% tax upon upon purchase !!. Many will say, why bother, just get a bigger bike?...but wor lass loves her 250r..and being so small, she has trouble riding owt different)