Can I drive with a 5% smaller spare tire?

3257 Views 12 Replies 9 Participants Last post by Mebarrera, Jan 21, 2022

DogsRule

Discussion Starter · Sep 23, 2021 (Edited)

Follow my lead here. I just blew a tire. It's a 225/65/16 and that's 2.5% larger than oem 215/65/16. Now the oem donut is 2.5% smaller than oem tires. So the spread on my Rene is now 5% between the donut and my other 3 rolling wheels.

Now I expect Jeep engineers to not have programmed the computers to do torque vectoring (or whatever term) when we use an oem donut spare as its only 2.5% smaller, but is TV activated at 5%? Is it causing the opposing brake caliper to drag and vector torque to the smaller tire ? Am I possibly damaging a rotor/caliper/pads by driving it this way ?

Help me with my logic please. I'm fuzzy from too much pasta for dinner.

Save

Reactions: 1

1 - 13 of 13 Posts

IDoMy0wnRacing

· #2 · Sep 24, 2021

On the Grand Cherokee SRT, the spare tire is 3.2% larger.
I understand it isn't a Renegade, but there is a bit of difference for you to reference.

I will admit, that I ran the same size spare on my Renegade Trailhawk. But I would like to think that your Renegade will send you an error message if it becomes angry with a different size tire, ABS, ESP, correlation error of some sore before anything gets hurt.

Save

Reactions: 1

raz-0

· #3 · Sep 24, 2021

The renegade 4wd system doesn't have torque vectoring, so no torque vectoring problems. If you were going to have problems, it would be with traction control and it trying to simulate a limited slip diff. But since it's open diffs up front and in back, and without the 4wd going, they aren't connected, it shouldn't' be too big of a problem. But I wouldn't put tons of miles on it. If the discrepency in rotations gets big enough, it could trip the ABS sensor check and then you get no ABS and no 4WD and no stability control until the unit clears the sensor error.

Save

Reactions: 2

Mud Pie

· #4 · Sep 24, 2021

While I'm no expert by any means, I believe using the temporary tire for it's designed purpose; to safely and slowly get you off the road, the size difference shouldn't be an issue. I'm talking getting off the road and to a tire shop. That's what they were designed for. Using them for short-term, less than 3 hours or so, should be fine. Run them until next pay-day, you're asking for problems. I've seen several cars running tiny temporaries as regular tires !! Just last week I saw a car running FOUR temporaries AND going 75 mph on the freeway !! I dropped a lane and hit the gas, I didn't want to be behind that disaster waiting to happen.

One of my friends, that knows nothing about vehicles, complained one time about how crappy the temps were and how fast they wear out. I asked how long he's been running it. "Almost a month". I laughed. He said a month IS temporary. But he is the same guy that buys 4 used mis-matched tires ("a tire is a tire") then complains about crappy handling and road noise, so....

See less See more

Save

Reactions: 2

puddlesplasher

· #5 · Sep 24, 2021 (Edited)

JFS said:
Follow my lead here. I just blew a tire. It's a 225/65/16 and that's 2.5% larger than oem 215/65/16. Now the oem donut is 2.5% smaller than oem tires. So the spread on my Rene is now 5% between the donut and my other 3 rolling wheels.

Now I expect Jeep engineers to not have programmed the computers to do torque vectoring (or whatever term) when we use an oem donut spare as its only 2.5% smaller, but is TV activated at 5%? Is it causing the opposing brake caliper to drag and vector torque to the smaller tire ? Am I possibly damaging a rotor/caliper/pads by driving it this way ?

Help me with my logic please. I'm fuzzy from too much pasta for dinner.

WOW

that's way over my head.

3% I recall being the maximum difference in wheel/tyre size.

However, in an emergency, no one will be examining your tyre. I was told professionally that the spare on another vehicle I know of that had a 19" spare was acceptable on an 18" wheel.

Tyre heights change all the dimensions, I am led to believe, whereby a vehicle can use a different sized wheel.

Naturally over short distances ie to get to the local garage and have the tyre repaired is acceptable.

Save

Reactions: 1

jeff1

· #6 · Sep 24, 2021

puddlesplasher said:
WOW that's way over my head.

3% I recall being the maximum difference in wheel/tyre size.

However, in an emergency, no one will be examining your tyre. I was told professionally that the spare on another vehicle I know of that had a 19" spare was acceptable on an 18" wheel.

Tyre heights change all the dimensions, I am led to believe, whereby a vehicle can use a different sized wheel.

Naturally over short distances ie to get to the local garage and have the tyre repaired.

who cares about tire size---it is a temporary fix one day tops and not over forty miles an hour hard braking could put you into a spin or a lane going in the opposite direction .your life your rules

Save

Reactions: 4

puddlesplasher

· #7 · Sep 24, 2021

Jeff you have said what I mean.

Thankyou kind Sir.

Save

Reactions: 2

Mud Pie

· #8 · Sep 24, 2021

jeff1 said:
who cares about tire size---it is a temporary fix one day tops and not over forty miles an hour hard braking could put you into a spin or a lane going in the opposite direction .your life your rules

Well done. You said in two sentences what I rambled on for two paragraphs.

Save

Reactions: 2

Jeepatron

· #9 · Sep 28, 2021

I used to have a Chevy Malibu spare, just because it was the same bolt pattern and was cheaper. A little smaller and I regret ever buying it. It got me out of binds sometimes but with my butt clenching extremely hard as some drivetrain component becomes unhappy and slaps the car around and service 4WD and engine lights come on. Fortunately they all go away when you get it back on all 4 regular sized wheels.

Save

Mike Gaines

· #10 · Sep 28, 2021

The sizes you show 225/65/16 and 215/65/16 the tire diameter are the same the 225 is just a little wider than the 215, you probably couldn't feel the difference, it won't hurt anything.

Save

puddlesplasher

· #11 · Sep 28, 2021 (Edited)

Mike the width is part of the formula for working out the % of deviation allowed ie

The height of the tyre is 65% of 225mm and 65% of 215mm.

146mm v 139.75mm

A 16" wheel is 400mm, now add on 2 heights for tyre wall ie 400 + 146 + 146 = 692mm overall width.

Same again but the smaller size: 400 + 139.77 + 139.75 = 679.5mm overall width.

Now you can work out the deviation between the 2 figures. Have a try.

Total difference is 13mm in width but whats that as a percentage deviation?

See less See more

Save

Reactions: 1

DogsRule

Discussion Starter · #12 · Sep 29, 2021

Lol. If nothing else, we’ve practiced our math.👍🏻
And I’ve talked myself into a 5th rim and 5th matching tire for a 5 wheel rotation.
And then talked myself into needing a pair of electric quick jacks.
Since I bought this thing, I’ve got the best equipped garage around. 🙂
Thank you Renegade.

Save

Reactions: 2

Mebarrera

· #13 · Jan 21, 2022

Jeepatron said:
I used to have a Chevy Malibu spare, just because it was the same bolt pattern and was cheaper. A little smaller and I regret ever buying it. It got me out of binds sometimes but with my butt clenching extremely hard as some drivetrain component becomes unhappy and slaps the car around and service 4WD and engine lights come on. Fortunately they all go away when you get it back on all 4 regular sized wheels.

I had a similar experience. The Renegade has 225 65 17 (a little larger than the original ones). Found a nail on one tire. Removed the tire leaking air and installed the spare (donut). Spare Tire Kit tire is 145/90R16. Drove to the tire repair and the vehicle was really unhappy. I did not drive faster than 60 km/h. It was as it was trying to apply the brakes all the time to compensate for the difference. The Renegade is a “North”, I tried disabling traction control (holding it down until it said ESC off) kept the 4x4 in Auto. But it did not matter.
It gave me the impression that driving like that for too long will brake or at least wear something down. There was no error on the dash or anywhere. But the feeling was really bad and turns were not safe at normal speeds (~20 km/h), it is winter here. Had to drive all the way with hazards on. I do drive on the highway, and if you do, therefore recommend getting a full size (preferably same size you currently have) spare tire.

Save

Reactions: 1

1 - 13 of 13 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.

Top Contributors this Month