To which part of the car are you going to attach the Hall sensor? You really can't mount it to the vehicle chassis since the vehicle suspension would constantly throw off the close alignment required by Hall effect sensors.
How large and heavy will the magnet be? You may need two to prevent unbalancing the wheel.
The cable from the sensor to the Uno will have to be shielded and be able to withstand constant flexing.
The suspension is from a 1994 Corvette. The back side (inside) surface of the wheel mounting plate, the plate that holds the 5 wheel studs, can readily be accessed. The magnets used with the sensors that I am looking at are very small, about 12mm in diameter and 3 mm thick, and I would be mounting 5 magnets, one at each wheel stud, so there would be no imbalance problem.
I think all Corvettes have an open driveshaft. Even those with IRS. Fasten/glue a magnet on opposites sides of the drive shaft. Need balance. Use a sensor to detect the magnets. Compute the wheel RPM based on the differential gear ratio and the sensor count per second.
A wheel is a very harsh environment with continuous vibrations and water, dirt and chemicals thrown up from the road. Not to mention the carelessness of tyre technicians when you get a puncture. Is it not possible to sense the speed somewhere away from all that - maybe on the inboard end of a propshaft?
I do all my own work, so tyre technicians are no worries.
I need to monitor the speed of two wheels, one front and one rear, so I can compare the wheel speed to determine the amount of rear wheel spin. The suspension I am using has reluctor wheels and ABS sensors, but they are the older two wire sensors and are not accurate below 10 MPH.
The picture below is an example of the hall effect sensor and magnet that I am considering.
Just wondering if anyone has used one of these, or similar.