Actually India lack the tech of minization of nuclear warhead, their technology is on par with the US in 1945s.
So they have very little means to deliver their little stone-age nuclear arsenal.
Even if they resort to nukes, their nuke delivered by stone-age Brownian-motion missiles could be well intercepted by Chinese Missile defense systems, and China can then feel free to wipe Indians out of earth, with a well justified reason.
I heard China has already deployed such missile defence system in Tibet, which, thanks to the highland, may even give them the capability to intercept the missiles at boost stage in India.
I think a war with India needs benefits, it should both expanding the terriority of China, and dismember India into pieces, otherwise, whats the point of starting a war?
At the minimum it should be: China take all disputed terrorities and some plus, and let the Northeast part of India gain independence, as well as solved the Kashmir problem once and for all, and restoring Sikkim kingdom and let Nepal take back what belong to them.