Pizza Cutter tire for a spare

[harper7]

I've suggested several times to possibly use what's referred to as a pizza cutter tire ,meaning tall and skinny, for a spare but never really knew if the 255/80/17 would fit. It fits and being skinny it tucks up nice under the back and much nicer then the 285/70/17 I had under there. They are pretty cheap at $229 a tire and almost $100 less then a 305/70/17 and I bet would be great offroad especially on a skinnier stock wheel.

I finally bought a 5th Konig X wheel and a 255/80/17 BFG KM2 which is a spec 33.3" diameter tire to use as my spare. My 305/70/17's tires are spec'd at 33.9" diameter so that will be within my tolerance to use as a spare if needed. As my 4 tires wear ,they will come even closer to a diameter match. Plus it's capabilities are a pretty close match in case I get a flat out on the other side of the boonies offroad to get me back.

Here's some pics....
Compared diameter to my tires I'm running.....

And compared to the 285/70/17 BFG KO I had on for 3+ years

 

[adam2562]

not a bad idea..

 

[HawgWild]

I just bought my 285's but when I decide to get some new tires, I am totally doing this!

Great idea!

 

[eddiebx]

That's pretty cool Gary, were you able to tuck it in there fully aired up? I remember reading some people having to let out some air from their 285s to squeeze it into the spare area.

 

[harper7]

That's pretty cool Gary, were you able to tuck it in there fully aired up? I remember reading some people having to let out some air from their 285s to squeeze it into the spare area.

I have it aired down to 20lbs but mainly to cushion it so it doesn't get wear marks from the underside and sucks up tight.I have onboard air with a tank to air it up in a couple of seconds if I need to use it.

One thing to check is those with KDSS TE might not fit as well as the rear KDSS sway bar is on the back side of the axle I believe and might be a limiting factor. I have about 1 1/2" clearance from my long track bar with it rearward as far as it will go so an even bigger diameter would have fit on mine.

One thing to note ,especially for those that live where road salt is used, is to take your spare tire down once and a while and spray some oil or wd40 on that crank with the chain up underneath to keep it from freezing up as a preventive maintenance type thing It's been a couple of years since I had mine down and it was getting sticky and I could see some corrosion on the gears so I lubed it up and ran it up and down a couple of times. They don't even use salt down here and I have very little rust up underneath. Would be a bad day if you need it and it froze up and wouldn't come down!

 

[Semi-Hex]

It's good to note that if you run me down, I'll be able to read your stickers.

 

[1000MPH]

Have you had a chance to drive around on it? Wondering if the size difference affects any of the electronic control devices.

 

[harper7]

Have you had a chance to drive around on it? Wondering if the size difference affects any of the electronic control devices.

No , but I have no worries at all about the size difference. My 305's are spec'd at 33.9" diameter new compared to the spares 33.3" new which it will stay new and my 305's will wear down. I can adjust the rolling diameter with air pressure some too. Heck I had a half worn 285/70/17 on there before for 3 years and didn't worry so this is the closest I've been.lol

My opinion on it is if you keep it within an inch or 2 sizes you'll be fine as that much fudgefactor should be built in considering wearing a running tire's tread down to the wear bars compared to a spares full tread can be close to an inch.

I was worried more that if I was far out on a tough trail and whether my spare would get me back if I cut a tire.Or in the case of my buddy who cut a tire sidewall and ruined his wheelin trip because his spare was junk.I feel I could throw this on the front and go anywhere that my 305's can go.

I did drive to work and back(20 miles) with a bigger tire on the front a couple of years ago to see how bad the bigger tire would rub before I bought the other 3!No lights,bells ,whistles ,axles flying off or anything happened .lol

 

[Narkhelek]

Interesting timing. I just today moved my BFG KM2 spare from my roof rack to the spare tire location. On a KDSS Trail edition the 255/80/17s fit but just barely.

 

[Matteblack]

This is a great idea. Will this fit on the factory Toyota spare wheel? Just wanted to confirm. Thanks for sharing this Harper!
MB

 

[eddiebx]

This is a great idea. Will this fit on the factory Toyota spare wheel? Just wanted to confirm. Thanks for sharing this Harper!
MB

I think you should be ok since the factory spare tire is already a 265, going to a 255 shouldn't cause much of an issue...

 

[proquip]

I think you should be ok since the factory spare tire is already a 265, going to a 255 shouldn't cause much of an issue...

I've posted on this topic before but wanted to share my logic, assumptions and calculations. An yes, I tend to over analyze things.

I'm making general assumptions about a possible scenario that might explain the allowed variance (as designed by Toyota engineers) while avoiding any undue impact to the vehicle's drivetrain or electronics (VSC, etc.). I have no inside knowledge of how the vehicle was actually designed.

For me, the best example of allowed variance between two tires would be an as-new stock spare and a mostly worn stock tire down to the minimum recommended 4/32 tread depth (used to be 2/32). For the stock 4Runner, we have a 265/70R17 Dunlop or Bridgestone tire that measures 31.7" in diameter with 11/32" of tread depth when new. If your tires were worn down to the 4/32 tread depth, you would have tires that are now 31.26" in overall diameter (see below).

31.7" - [2 x (11-4)/32] = 31.26"

So, you could end up running a 31.7" diameter tire (spare) and a 31.26" diameter tire (worn) at the same time. If you apply that ratio (31.26 / 31.7) to an oversized tire setup, in particular the 32.8" diameter of a 285/70R17 tire, I calculate that your spare tire could measure 32.3" in diameter and still keep to the above ratio.

32.8" x (31.26 / 31.7) = 32.34"

For me, being a fan of pizza cutters because the spare would tuck in a bit more than the current spare, I'm seriously considering either a worn 255/80R17 BFG KM2 (32.4" at 4/32 tread depth, but just haven't seen any for sale in my area), or perhaps a new Goodyear MTR Kevlar in 255/75R17 which runs a bit tall at 32.3". As my new tires wear down, the variance between the two possible tires actually narrows, which is a good thing.

I've seen a lot of debate on this topic in the past, but I wanted to put some logic and numbers to see where I landed. I think the options I'm pursuing would be consistent with the worn tire / new spare scenario that in my mind must have been factored when the drivetrain and electronics for the 4Runner were designed. Then again, what do I know?!?

 

[eddiebx]

I've posted on this topic before but wanted to share my logic, assumptions and calculations. An yes, I tend to over analyze things.

I'm making general assumptions about a possible scenario that might explain the allowed variance (as designed by Toyota engineers) while avoiding any undue impact to the vehicle's drivetrain or electronics (VSC, etc.). I have no inside knowledge of how the vehicle was actually designed.

For me, the best example of allowed variance between two tires would be an as-new stock spare and a mostly worn stock tire down to the minimum recommended 4/32 tread depth (used to be 2/32). For the stock 4Runner, we have a 265/70R17 Dunlop or Bridgestone tire that measures 31.7" in diameter with 11/32" of tread depth when new. If your tires were worn down to the 4/32 tread depth, you would have tires that are now 31.26" in overall diameter (see below).

31.7" - [2 x (11-4)/32] = 31.26"

So, you could end up running a 31.7" diameter tire (spare) and a 31.26" diameter tire (worn) at the same time. If you apply that ratio (31.26 / 31.7) to an oversized tire setup, in particular the 32.8" diameter of a 285/70R17 tire, I calculate that your spare tire could measure 32.3" in diameter and still keep to the above ratio.

32.8" x (31.26 / 31.7) = 32.34"

For me, being a fan of pizza cutters because the spare would tuck in a bit more than the current spare, I'm seriously considering either a worn 255/80R17 BFG KM2 (32.4" at 4/32 tread depth, but just haven't seen any for sale in my area), or perhaps a new Goodyear MTR Kevlar in 255/75R17 which runs a bit tall at 32.3". As my new tires wear down, the variance between the two possible tires actually narrows, which is a good thing.

I've seen a lot of debate on this topic in the past, but I wanted to put some logic and numbers to see where I landed. I think the options I'm pursuing would be consistent with the worn tire / new spare scenario that in my mind must have been factored when the drivetrain and electronics for the 4Runner were designed. Then again, what do I know?!?

Great info and calculations! It really helps you visualize it when all the numbers are sitting in front of you.

What you are saying makes perfect sense, but I think [MENTION=79556]Matteblack[/MENTION] was talking about if a 255/80R17 would physically fit (rim width/diameter) on the factory spare wheel or not. At least that's what I think he was asking?

 

[thebwlife]

This is a great idea. Will this fit on the factory Toyota spare wheel? Just wanted to confirm. Thanks for sharing this Harper!
MB

It will fit just fine.

 

[Matteblack]

Thanks folks, will post when I do this!

 

[Matteblack]

Has someone done this on a TE?

 

[Matteblack]

Just checked into this at my neighborhood Les Schwab and according to the measurements we took TE's will not offer enough space for the taller tire. Has anyone with a TE experience otherwise?

 

[proquip]

Just checked into this at my neighborhood Les Schwab and according to the measurements we took TE's will not offer enough space for the taller tire. Has anyone with a TE experience otherwise?

[MENTION=58068]Narkhelek[/MENTION] in this same thread has them. A few others on the forum have them as well (e.g. [MENTION=77604]SEP[/MENTION]) so you should be fine. Check with them for direct feedback.

 

[Matteblack]

If someone has done this on a KDSS TE could you post a pic?

Thanks,MB

 

[DannyLlama]

If someone has done this on a TE could you post a pic?

Thanks,MB

The picture that Harper posted is a TE bumper.. He did the conversion.

Is that what you meant?