[rumrunner]

on the verge of putting my winter tires on, but here's the situation

last time I got new tires (April 2021) I changed tire size & bought 5, so my spare would match
... so if I put my winter tires on (which are the OEM size) can I leave that new spare mounted in the cargo area? would it be ok to use in the rear, if I get a flat? or shud I not risk it & put the OEM sized spare on?

both spare tires are new full size tires
the OEM spare was only used once for a cpl hundred miles
the winter tires have a few seasons on them

the OEM size is 225 60 18
tires on the car now are 235 55 18

so can I use winter tires that are 225 60 18 but keep my spare that is 235 55 18?

I guess I know the answer: "yes change all 5 tires" because, why not?

 

[sanghill]

The tires on all 4 wheels need to be the same diameter.
There is a paragraph in the Owner's Manual that says how nearly the tire sizes need to match.

 

[BurtonRW]

That's also why it's important to do a proper 5-tire rotation when you rotate your tires. It's no good to have a matching spare that's not actually matching because it has no wear.

-Rob

 

[Mark_]

Well... to put things in perspective :

Would you use the Cherokee donut spare if you had one and needed a spare ?

Donut spare : 165/80/17 = 27.4''
OEM : 225/60/18 = 28.6''
Other : 235/55/18 = 28.2''

4.2% difference between OEM and donut.
1.4% difference between OEM and other.

Math looks good to me.

 

[MikeR.]

I believe the manual says within 5%, but I would have to go back to check.

 

[Gator]

Well... to put things in perspective :

Would you use the Cherokee donut spare if you had one and needed a spare ?

Donut spare : 165/80/17 = 27.4''
OEM : 225/60/18 = 28.6''
Other : 235/55/18 = 28.2''

4.2% difference between OEM and donut.
1.4% difference between OEM and other.

Math looks good to me.

yeah, I would think if used as an emergency spare, not a replacement. seems logical….

 

[rumrunner]

Well... to put things in perspective :

Would you use the Cherokee donut spare if you had one and needed a spare ?

Donut spare : 165/80/17 = 27.4''
OEM : 225/60/18 = 28.6''
Other : 235/55/18 = 28.2''

4.2% difference between OEM and donut.
1.4% difference between OEM and other.

Math looks good to me.

ok thank you! the full size spare is better than the donut. & since the 2 sizes are so close, I can keep the spare I have in there now, for the next 6? weeks

 

[Flybynightcru]

ok thank you! the full size spare is better than the donut. & since the 2 sizes are so close, I can keep the spare I have in there now, for the next 6? weeks

I think you'll be alright...😎

 

[sqenixs]

Well... to put things in perspective :

Would you use the Cherokee donut spare if you had one and needed a spare ?

Donut spare : 165/80/17 = 27.4''
OEM : 225/60/18 = 28.6''
Other : 235/55/18 = 28.2''

4.2% difference between OEM and donut.
1.4% difference between OEM and other.

Math looks good to me.

I was told at a tire shop when I asked this, that subarus get mad if you go more than 4/32nds different in size between any tires. Which would be 6.25%, so perhaps the 5% thing is appropriate. So for example, on my jeep I have been too lazy to replace my summer tire in the spare area with my OEM full size spare. So if I got a flat tire with my winter tire 235/65/17 I would be replacing with a 265/65/17, which is probably too much of a difference. But if I instead replaced with my 245/65/17 it should be ok. This is good news to me since I have been trying to sell that stupid OEM spare for years. Now I can just keep it as a spare for the winter.

 

[Mark_]

I was told at a tire shop when I asked this, that subarus get mad if you go more than 4/32nds different in size between any tires. Which would be 6.25%, so perhaps the 5% thing is appropriate. So for example, on my jeep I have been too lazy to replace my summer tire in the spare area with my OEM full size spare. So if I got a flat tire with my winter tire 235/65/17 I would be replacing with a 265/65/17, which is probably too much of a difference. But if I instead replaced with my 245/65/17 it should be ok. This is good news to me since I have been trying to sell that stupid OEM spare for years. Now I can just keep it as a spare for the winter.

Huh ? How does a 4/32nds difference translate into 6.25% ?

4/32nds difference (this is radius, not diameter) is 1/8'' or 3mm. So X2 for diameter = 1/4'' or 6mm.
Now on a 225/60/18 tire which I took for the math : 28.6'' is spec. Go up 1/2'' (now this is double your 4/32nds) and you're at 29.1'', right ? Well that is a 1.7% difference. So divide by 2 and you're under 1% difference.

Say your guy misspoke and meant the difference between a new tire and one down to 4/32nds : new is usually 11/32nds (some at 12, others at 10). So the difference there would be 7/32nds between new and worn down to 4/32nds.
Ok my head hurts, but a 7/32nds difference = 14/32nds in diameter, so just under 1/2''. Remember the math above with a 1/2'' diameter difference on a 225/60/18 ? 1.7%... So I dunno where they got 6.25%...

If a Subi can't handle a 0.85 or even a 1.7% tire size difference, I'd go shopping for another car

 

[rumrunner]

nobody wants OEM temp spare donuts. I've got 2 in my basement, Cherokee & Corolla. I only keep them because when I trade in cars, I put them back in the car(s) & I keep the full size wheel & tire because I can sell them or use them in the next car

 

[UmpJJ]

I always thought that donut spare had a speed limitation on it as well. I went with a full size spare so I can keep on truckin' at highway speed to finish whatever highway trip I'm in the middle of. Is there a flaw in my logic?

 

[Mark_]

I always thought that donut spare had a speed limitation on it as well. I went with a full size spare so I can keep on truckin' at highway speed to finish whatever highway trip I'm in the middle of. Is there a flaw in my logic?

Correct, I believe they are rated for max. 50mph. They can go faster, but 50 is there for safety reasons that also include less grip, smaller diameter so higher revs on that wheel and I'm sure a safeguard knowing most people don't care for their spare (= grossly inderinflated).

 

[sanghill]

THE solution: get factory tow whether you tow or not.
Read your Owner's Manual and/or the tire sidewall.

 

[Mark_]

THE solution: get factory tow whether you tow or not.
Read your Owner's Manual and/or the tire sidewall.

Tow group, or AD2, which gets full-size spare also.

 

[rumrunner]

I have ADI. it was a no brainer to just buy a wheel & tire

 

[rumrunner]

I went with a full size spare so I can keep on truckin' at highway speed to finish whatever highway trip I'm in the middle of

absolutely. handful of years ago, picked up Daughter at college, 200 miles away. got to campus & ripped a tire on a curb. yeah brilliant Dad. put on the full size spare, loaded the dorm room into the Jeep & drove 200 miles home

 

[Leems]

I have four LT265/65R17 tires, but my P245/65R17 spare is still inside the compartment untouched. The new tire size won't fit in there and I know that I could put the larger tire on the Rhino Rack roof platform, but choose not to.

My 'plan' is to limp to a nearby location where I can get the proper size tire changed over. I've actually been thinking about just buying the LT replacement and just leave it in the garage until needed, but spending 4 months in one location and 8 in another may make that idea less than ideal. I could order the LT version and typically get it delivered in a few days, worst-case. There doesn't seem to be a perfect solution, unless that is it.

 

[MikeR.]

I have four LT265/65R17 tires, but my P245/65R17 spare is still inside the compartment untouched. The new tire size won't fit in there and I know that I could put the larger tire on the Rhino Rack roof platform, but choose not to.

My 'plan' is to limp to a nearby location where I can get the proper size tire changed over. I've actually been thinking about just buying the LT replacement and just leave it in the garage until needed, but spending 4 months in one location and 8 in another may make that idea less than ideal. I could order the LT version and typically get it delivered in a few days, worst-case. There doesn't seem to be a perfect solution, unless that is it.

Usually if you air it down, you can put it in. I have 265/70s, so I'm in the same boat. Usually I just leave mine in the garage. I do carry plugs and a compressor thought to get off the trail. Worse case, I'll call someone to go grab my spare and bring it to me. If I'm going out of town, I'll throw it up top, or in the back depending on how much space I have.

 

[Gary Kline]

Or take out the black plastic liner if you just need a little more space