Update Elantra Values (#1430)

* Update Elantra Values one last time

I got the params learner values from EON. These are the values it settled on after driving over a week.

* Include Stiffness Params Value.

* Update interface.py

selfdrive/car/hyundai/interface.py

@@ -65,8 +65,8 @@ class CarInterface(CarInterfaceBase):
       ret.lateralTuning.pid.kf = 0.00006
       ret.mass = 1275. + STD_CARGO_KG
       ret.wheelbase = 2.7
-      ret.steerRatio = 13.73   #Spec
-      tire_stiffness_factor = 0.385
+      ret.steerRatio = 15.4            # 14 is Stock | Settled Params Learner values are steerRatio: 15.401566348670535
+      tire_stiffness_factor = 0.385    # stiffnessFactor settled on 1.0081302973865127
       ret.lateralTuning.pid.kiBP, ret.lateralTuning.pid.kpBP = [[0.], [0.]]
       ret.lateralTuning.pid.kpV, ret.lateralTuning.pid.kiV = [[0.25], [0.05]]
       ret.minSteerSpeed = 32 * CV.MPH_TO_MS