Taller tire profile
 

So I have a Zongshen bike(ZS250GY-7), it’s similar to the csc tt 250 but with basic suspension and a 19” front tire.

My rear tire is already very worn(4000km~ 2500miles), they are the same tire that the csc tt 250 comes with( centrao dual purpose) and so far I really like them. The problem is they are not available to buy in my country.

So far the only options I found locally that fit the weird (19f-18r) configuration are the Michelin Sirac(80/20), Ax41 adventure cross and Rinaldi rt36.

I am really liking the Ax41 however the profile is 100/90-19 which is a taller tire compared to the stock 90/90-19, what can I expect from this change? The rt36 are very cheap but from what I researched they are bad in wet conditions.

Also if I wanted to change the front rim to a 21 do I need to the change something in the rear? I guess I would also need to adjust the speedometer.

You can expect the front to be raised by 9mm.

Might actually fix the optimistic speedometer.