Yes, they do.
when you get bigger tires, or different rear end gears.
Jet Accu Speed Speedometer calibrator. It adjusts your speedometer for bigger tires or gear change. Only works on automatic transmissions.
You recalibrate it because bigger tires mean different speeds... for example, lets say your car had 14 inch tires... and your speedometer is saying that you are going 50, if you add 20 inch tires which is 6 inches bigger, you might be going around 60-70. No need to get a speeding ticket. Bigger tires cover more road then smaller tires, for example for ever 1 turn from a 20 inch tire is like 1 and ahalf turns from a 14 inch... Hope Ive helped you understand why :)
If you change your tyre size without switching out the rear end gears to compensate for it, you'll run lower speeds at higher RPMs (which gives you more pulling torque, but kills you on mileage and overall top speed), and your speedometer will show you going faster than you actually are (unless it adjust it to compensate for the smaller tyres).
The 99 tires are much bigger than the 90 tires. With the smaller tires on the 99 you would be going slower than indicated on the speedometer.
slightly bigger tires
The size of tires can effect that accuracy of a speedometer. Larger tires will cause the speedometer to read less than you are actually going.
Putting larger tires on your car will give you higher top spee with less torque. However, changing the tire size will make your speedometer inaccurate.
Yes, if you get bigger tires it will say you are going slower than you are, and visa versa, you can go to a mechanic to get it recalibrated
Yes, they will fit. Be aware that if the wheels are not the same diameter your speedometer will be off unless you change tires to compensate.
The Rims will fit as long as they are the same number of studs and puting 17 inch rims on will not screw up your speedo as long as the tires you use have the same outside diamiter. If they are the tires that came with the original 2007 silverado they will be the same outside diamiter as your 16" wheels and tires You can also adjust for larger tires on the speedometer with a hypertech controller.