# 4 wheel drive at 75 mph **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** transmissions, lexus, wheels\ **Created:** [July 7, 2009, 11:41pm UTC](https://community.cartalk.com/t/4-wheel-drive-at-75-mph/33047 "2009-07-07T23:41:23Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![jalamo44](https://avatars.discourse-cdn.com/v4/letter/j/71e660/32.png) [@jalamo44](https://community.cartalk.com/u/jalamo44)\ **Post date:** [July 7, 2009, 11:41pm UTC](https://community.cartalk.com/t/4-wheel-drive-at-75-mph/33047/1 "2009-07-07T23:41:23Z")
We discovered that one of our tires is larger than the others, which we were told would make the computer think the other tires were slipping and activate 4 wheel drive. We have driven quite a distance on the Interstate at 70 to 75 mph. Would this cause damage to the transmission or any other system? ---
**Author:** ![oldschool](https://avatars.discourse-cdn.com/v4/letter/o/e19adc/32.png) [@oldschool](https://community.cartalk.com/u/oldschool)\ **Post date:** [July 7, 2009, 11:47pm UTC](https://community.cartalk.com/t/4-wheel-drive-at-75-mph/33047/2 "2009-07-07T23:47:20Z")
Now I get to say it,have you checked your owners manual for this info? How much difference in tire size is there? ---
**Author:** ![FoDaddy](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/fodaddy/32/717_2.png) [@FoDaddy](https://community.cartalk.com/u/FoDaddy)\ **Post date:** [July 7, 2009, 11:48pm UTC](https://community.cartalk.com/t/4-wheel-drive-at-75-mph/33047/3 "2009-07-07T23:48:54Z")
What kind of vehicle are we talking about? ---
**Author:** ![UncleTurbo](https://avatars.discourse-cdn.com/v4/letter/u/e9a140/32.png) [@UncleTurbo](https://community.cartalk.com/u/UncleTurbo)\ **Post date:** [July 7, 2009, 11:51pm UTC](https://community.cartalk.com/t/4-wheel-drive-at-75-mph/33047/4 "2009-07-07T23:51:35Z")
How did one tire suddenly become larger than the others? What does the owner’s manual say? You have a unique SUV, a hybrid Lexus. This SUV uses transmission and driveline components that are unique to this vehicle. I don’t have enough knowledge of the Lexus hybrid system to make an informed opinion. I would advise getting 4 matching tires on the SUV. If you have a problem it could be an expensive repair. ---
**Author:** ![mcparadise](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/mcparadise/32/32_2.png) [@mcparadise](https://community.cartalk.com/u/mcparadise)\ **Post date:** [July 7, 2009, 11:55pm UTC](https://community.cartalk.com/t/4-wheel-drive-at-75-mph/33047/5 "2009-07-07T23:55:47Z")
Without knowing what vehicle you drive it’s impossible to say. There are 4WD vehicles and there are AWD vehicles, and there’s quite a bit of difference between and within these two vehicle types. On certain vehicles one tire with a larger diameter means almost nothing. On other vehicles it’s a prescription for disaster. What are you driving? ---
**Author:** ![lion9car](https://avatars.discourse-cdn.com/v4/letter/l/59ef9b/32.png) [@lion9car](https://community.cartalk.com/u/lion9car)\ **Post date:** [July 8, 2009, 12:23am UTC](https://community.cartalk.com/t/4-wheel-drive-at-75-mph/33047/6 "2009-07-08T00:23:50Z")
Don’t you love the posters who think we’re mind readers? 🙂 ---
**Author:** ![dagosa](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/dagosa/32/9837_2.png) [@dagosa](https://community.cartalk.com/u/dagosa)\ **Post date:** [July 8, 2009, 1:13am UTC](https://community.cartalk.com/t/4-wheel-drive-at-75-mph/33047/7 "2009-07-08T01:13:13Z")
From what I’ve read, and not to negate the difference in tire diameter; the Lexus Hybrid uses a third electric motor to drive the rear wheels w/o the need of a center differential. About as fail safe as you can get for the described situation but no guarantee of no drive train stress elsewhere in my opinion.