Need to know what size i can go up too

Currently front tire is a 100/90-19
Rear is 140/90-15


Im looking at buying some white walls but if i want to go a little bigger in both front and rear how much more can i go with the stock wheels before i have to upgrade wheels looking at beefing up the front with almost wanting to match the rear tire size can anyone help me out thanks in advance

Mkg

Bit late but if you do any research on tyre sizing you'll see stock sizes are usually the biggest that can safely be fitted on the 'narrow' stock rims. Fitting wider tyres will just cause them to pinch and wear out a LOT faster.
It wouldn't be a big deal to get a rear rim and fit it to front hub, (or use rear rim on front and get wider rim for rear?) custom spokes will be a bit spendy though ($100+)

you might also want to have a look at how wide a tyre will fit between the forks, especially if you're going to change rims

Add in another easy 10% on the width when cold to the tires runnong when hot. Wathc for binding near front and rear forks and rear chain and chain guard.