An example using local class which groups some data

DE10Controller.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class DE10Controller : MonoBehaviour
{
    [System.Serializable]
    public class Wheel
    {
        public List<Rigidbody> wheels;
        public float wheelMass = 600;   // mass of each wheel pair without flange mass; i.e. twice the mass of 1 wheel without flange mass
    }

    
    public float targetVelocity;    // target speed of rotation
    public float torque;    // a torque to be applied to each wheel
    public Wheel wheel;     // a group of setting related to wheels

    // Start is called before the first frame update
    void Start()
    {
        foreach(Rigidbody rb in wheel.wheels)
        {
            rb.mass = wheel.wheelMass;
        }
    }

    // Update is called once per frame
    void Update()
    {
        foreach (Rigidbody rb in wheel.wheels)
        {
            rb.mass = wheel.wheelMass;
            rb.AddTorque(0, 0, torque);
        }
    }
}