Installing a tire with a different size than the recommended specifications for your motorcycle can have several implications. Let's compare the two sizes you mentioned:
90/90/18: This represents a tire with a width of 90 millimeters, a sidewall height that is 90% of the tire's width, and it fits on an 18-inch wheel.
2.75-18: This size is typically expressed in inches and represents a tire width of 2.75 inches that fits on an 18-inch wheel.
If you were to install a 90/90/18 tire instead of a 2.75-18 tire, the following effects may occur:
Fitment: The tire with a different size might not fit properly on the rim or within the bike's frame. It could rub against components, affecting the handling and safety of the motorcycle.
Handling: Changing the tire size can impact the bike's handling characteristics. A wider tire may alter the contact patch with the road surface, affecting traction, cornering abilities, and stability. The bike's overall balance and maneuverability may be compromised.
Speedometer and Odometer Accuracy: A tire with a different size can affect the accuracy of your motorcycle's speedometer and odometer. Since the circumference of the tire changes, the readings provided by these instruments may no longer be accurate.
Suspension and Clearance: The change in tire size may affect the suspension setup and clearance of the motorcycle. It could potentially cause issues with the bike's suspension travel or interfere with other components, such as fenders or swingarms.
It's important to consult your motorcycle manufacturer's guidelines or seek advice from a professional mechanic or authorized dealer regarding the appropriate tire size for your specific make and model. They can provide accurate recommendations based on the bike's specifications, ensuring optimal performance, safety, and compliance with legal requirements.