A wider tire on a narrow rim does NOT give you a bigger contact patch, because the narrow rim for the big tire size pinches the bead together and crowns the tread more severely, generating a smaller radius. Added to that, the sidewall angle increases over what is recommended for the tire, making the tread crown unstable with respect to the rim position. To stiffen the sidewall and improve tread posion w.r.t rim, higher pressures are needed Which further crown the tire reducing contact patch further.
Worse, as the center of the tread wears down, the tread "squares off". This creates the need for ever increasing counter steer as the tire wears, and impacts "handling" of the CB500/Cb550 which generally has pretty neutral steering and balance in the corners.
New tires will feel great initially. Near end of life, you will have learned to compensate for the ill effects. Leading you to believe the next new tire you replaced it with is far superior to the old you just replaced. But, the pattern of wear and handling degradation will then repeat.
Tire salesmen love to sell you a bigger more expensive tire. Better profit for them this way. And they probably have in it stock to sell immediately. Also the bigger tire on narrow rims wears more rapidly, putting you back in their store sooner for yet more profit.
Finally, a wider tire weighs more than than the stock size. Placing more stress on shocks that are trying to keep the tire from bouncing off the pavement. Your contact patch does nothing for you if the tire isn't on the pavement. Further, adding weight to the bike, makes it slower, as the engine has to twirl the bigger tire overcoming more inertia, wheel and bike overall.
Good luck with your decision path.
Cheers,
