Difference between daily tires and spare?

[Discount Tire]

Discount tire is not the best source for this info. Your owner's manual has a section on "dissimilar size spare" tires which has all the info you need. You can use one, but it should be temporary (long enough to drive to the shop and have your damaged tire repaired), and the computer may disable the 4WD system until you put the right size tire back on.

OEM Vehicle Manufacturers typically do not make tire mixing guidelines for their
AWD systems readily available to support, so this is great info @Mark S! Industry standard recommends four matching tires to avoid potential drivetrain issues.

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[Bamsi]

The manual isn't clear about the details regarding when the system disables 4WD. I would assume it would be almost immediate if you are using a donut, but any significant difference in overall circumference will likely have the same result eventually.

The 4WD system uses sensors to compare speeds for all four wheels. When one or more spin at a different speed from the rest clutches engage in the power transfer unit (PTU) to divide power from front to rear. A persistent speed difference, such as would occur with one tire of significantly different circumference, would keep the PTU clutches locked up all the time. The PTU in non-Badlands models is air-cooled, and therefore not designed for full-time operation. It would quickly overheat due to the constant friction on the clutches, causing premature wear. That's why the system disables itself if it senses a persistent difference in speed between the four wheels.

If your spare tire is the same circumference as the rest of your tires you should be fine.

Thanks Mark. I am thinking on using 235 70 17 that are 30" in diameter, the OEM spares are either 28 5 or 29 inches. I do not think a 30 inches will fit the spare well. That is what motivated the original question.

 

[Dude]

OEM Vehicle Manufacturers typically do not make tire mixing guidelines for their
AWD systems readily available to support, so this is great info
Industry standard recommends four matching tires to avoid potential drivetrain issues.

That’s true DT but the tire industry also loves to sell tires and tire services. This is the way

 

[Escape2Bronco]

So if I'm understanding this correctly then if I'm somewhere that I'm having to use 4wd and I get a flat and change it it will disable 4wd?? I replaced the donut on my BB for a full size tire and wheel. I put one of the original street tires that was on it when I bought it to the spare. And I put 225 65 17 Toyo tire's on it. The spare is the same size. Will I have trouble with 4wd then?

Easy problem to solve. Get a spare to match the rest. Or... don't worry about it. I chose to get a new spare and not worry about it.

 

[Robink]

Easy problem to solve. Get a spare to match the rest. Or... don't worry about it. I chose to get a new spare and not worry about it.

I will get another Toyo tire eventually but I've spent so much money on this car already it's going to have to wait a bit. Hey thanks everyone for the good information!!!!

 

[gatornek]

Thanks Mark. I am thinking on using 235 70 17 that are 30" in diameter, the OEM spares are either 28 5 or 29 inches. I do not think a 30 inches will fit the spare well. That is what motivated the original question.

Do you know whats the largest diameter that will fit the spare wheel well?

 

[Meanderthal]

Do you know whats the largest diameter that will fit the spare wheel well?

I think 29.5" is just about the limit for tire size that will fit in the well. Even then, it requires some removal of the padding (at least in a Badlands).

 

[Bamsi]

Do you know whats the largest diameter that will fit the spare wheel well?

Nope! That is what I want to figure out, maybe getting an answer tomorrow...

 

[magicbus]

So if I'm understanding this correctly then if I'm somewhere that I'm having to use 4wd and I get a flat and change it it will disable 4wd?? I replaced the donut on my BB for a full size tire and wheel. I put one of the original street tires that was on it when I bought it to the spare. And I put 225 65 17 Toyo tire's on it. The spare is the same size. Will I have trouble with 4wd then?

Do you actually have 4WD in your trim level. Do you have the 4WD locking button? I can see where 4WD would be disabled when LOCK is selected with a non-matching wheel, but not in normal AWD mode. I’m pretty sure t’s why the BS comes with a full size spare.

 

[Robink]

Do you actually have 4WD in your trim level. Do you have the 4WD locking button? I can see where 4WD would be disabled when LOCK is selected with a non-matching wheel, but not in normal AWD mode. I’m pretty sure t’s why the BS comes with a full size spare.

No. You are correct.

 

[Escape2Bronco]

Do you know whats the largest diameter that will fit the spare wheel well?

The optional 235/65-17 fits in the Badlands without any modifications.

 

[Bamsi]

The optional 235/65-17 fits in the Badlands without any modifications.

I know. But will be using 235 70 17 instead, 29" vs 30"

 

[davidg4781]

That’s true DT but the tire industry also loves to sell tires and tire services. This is the way

To be fair, I stopped at a Discount Tire and talked to the guy about buying a Subaru. He talked me out of buying an AWD car because of the need to keep all tires within the same tread depth.

Then two years later I buy a Bronco Sport .

 

[Dude]

To be fair, I stopped at a Discount Tire and talked to the guy about buying a Subaru. He talked me out of buying an AWD car because of the need to keep all tires within the same tread depth.

Then two years later I buy a Bronco Sport .

Same for me with my 2016 Subaru Forester but was not DT - new set of 4 tires and just 4 months (under 3k miles) driving a road hazard damaged 1 tire beyond repair. Probably only 1/32 tread used (guessing that from memory) and Firestone would not install just 1 new tire because of Subaru’s documented policy.

I had to sign a waiver to get just the 1 tire.

 

[davidg4781]

Same for me with my 2016 Subaru Forester but was not DT - new set of 4 tires and just 4 months (under 3k miles) driving a road hazard damaged 1 tire beyond repair. Probably only 1/32 tread used (guessing that from memory) and Firestone would not install just 1 new tire because of Subaru’s documented policy.

I had to sign a waiver to get just the 1 tire.

Well I just learned DT buys back tires. I don't know if it's all locations and all tires. But if this is the case, at least I would get something for the other 3 tires.

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