Is it safe to drive my Jeep if the spare has a larger WHEEL size (18") than the other 3 wheels. The spare is a 245/65R/18. The other 3 are 245/70R/17. My guess is I CANNOT drive any significant distance with this configuration.

I wouldn't recommend it. If that tire is larger than the rest it throws off the center of balance. Increases the risk factor of something going wrong. Strongly recommend they're all the same size.

Anne, we wouldn't recommend driving a long distance with your tire being a different size than the rest. Please contact our service department at 315-637-3101 to discuss further. Thank you, Romano Chrysler Jeep

There's your answer 👍