am half-heartedly researching 13 inch wheels for my GTS Supertech.
maybe these https://www.sip-scootershop.com/en/product/rim-sip-series-pordoi_MV650814
would also have to make up mind what tire sizes ...
original sizes
front 120/70-12 diam 18.6" width 4.7" sidewall 3.3"
rear 130/70-12 diam 19.2" width 5.1" sidewall 3.6"
sip recommended for their rims
front 120/70-13 diam 19.6" width 4.7" sidewall 3.3"
rear 140/60-13 diam 19.6" width 5.5" sidewall 3.3"
have seen other people use
front 130/60-13 diam 19.1" width 5.1" sidewall 3.1"
note the original front is .6" smaller diam yet sip recommends using same front+rear diam. probably why some others have used the 130/60 to get approx the original axial height difference front vs rear.
Is a half inch diam increase really worth it? Desire: betteer handling at higher speeds. Can live with the slight lost of accel
thoughts?