How big of a spare tire can i fit under the truck

Your assumption is mathematical, not practical. If you buy larger aftermarket tires and get stuck in the middle of fucking nowhere with a stock spare and have to get home alone over difficult conditions (that may well shred the OEM tire), and then drive on a freeway for any distance to find a shop, that's not a lot of fun and not safe or good for you or your truck. Not so much giving a damn about upfront mileage or cost.
And what if I don't rotate that 5th in and end up at the point I need to buy tires and decide to change brand, or more importantly, size, and then I have to deal with selling a fifth new tire that is no longer useful to me? That's another PITA.

 

Most people pick a size and stay with it. My assumptions up front is for a regular owner, like most of us. They won't change size, they will buy the same size next time, they will rotate, etc.

Sure, I can give you a situation where you need to buy eight tires but is that normal? Nope. Just like with your example. Who upsizes tires? Not many people. Who goes out in the middle of nowhere? Not many. Who that does go out in the middle of nowhere gets a flat? Not many. Pretty sure my assumptions cover way more people than your special scenario.
Have a great night bro.

 

BFG recommends a 5 tire rotation, but for those of us who have only 4 stock alloys with TPMS sensors and a steel spare rim, that 20% overall treadwear saved will not pay off the rotations and balancing. So, yeah- I’m a 4 tire rotator. In fact, so much so that I scribbed 4 small letters into my alloys next to the valve stem “a, b, c and d” to keep track of the rotation patterns, as I’ve been following this one on four different Toyota trucks with BFG’s over the last 22 years with great tire wear results:

 

Pic of how you cut your muffler? Planning on this his weekend.

 

Same pattern I use.
If you go by the owner's manual, the tires will have heel-toe wear.

 

I was wondering if the spare had TPMS or not just the other day!

 

Haha your "assumption" of people not up sizing tires response in a thread called "How big of a spare tire can I fit in the under the truck" is invalid and nulled voided. Your "assumption" also takes into account 10k rotation when toyota recommends 5k rotations which only leaves you 5k left on a single $200/50k tire with a remaining $20 value. Your "assumptions" and calculations can not calculate true wear evenly across all 5 tires therefore that actual 10% left tread is minuscule when it comes to $ real world situation. Also your "assumption" doesn't account for an air tired or even cover dry rot tire that has to be replaces anyways with no wear costing even more. At this point why even carry a spare tire... when no one goes in the middle of nowhere?

I run a 285/75/16 with an exhaust chop over axle and hammered back support.

 

All I had to do was push the exhaust about 1/2 inch toward the passenger side. There is quite a bit of movement on the exhaust thanks to the rubber bushings on the hangers.

 

Haha I love how people try to justify passionate decisions instead of using logic.
Michelin recommends replacing tires every 10 years. Industry standard recommends every 6 years. Using my simple scenario and assumptions you need tires every 2 1/2 years. That means you can leave your original spare under there for 100K miles or five years and still be OK in regards to dry rot.
Bottom line: Five tire rotation does not give you a 20% savings. At best it is the same as a four tire rotation. Even if you upsize when the truck is new and add a upsized spare, five tire rotations save you nothing. It's a wash either way. It works out the same money.

 

I do love the technical passion on tire rotation! I'm a sucker to looks though, so plan to keep the dirty spare beneath my truck at all times. With all the road grease and grime on it, I'd never get it clean enough to look like the other three. (yes, looks matter for me!)

 

People change five tires because their dad did it and their granddad did it or they heard it from a friend of a mechanic or something. It was a wash back then and it definitely is a wash now with TPMS and everything. It's like oil change duration arguments haha.

 

It's funny...I use my spare when I do a 4 tire rotation, because I'm only jacking one wheel at a time.

 

Exactly why I rotate 5 tires

 

I only use the spare as a 'placeholder'; it goes back underneath.

 

This is exactly what I am about to do. Upgraded all 4 wheels to 17" with Wilpeaks 265/70r17 so I've been meaning to upgrade the 16" spare to a 265/75r16. Thanks for confirming fitment!

 

Your assumption that people drive 20k miles a year is about double what I do. Avg driver does 13.5k.

Id rather use the spare instead of replacing a "brand new" tire every 6 years or so.

It's a case of what I say rather than do. 5 tire rotation is better. But it's an extra step so I don't do it lol. Will probably change my tune the first time I need a spare and the mechanism is rusted shut.

 

My rationale for going to a 5 tire rotation is, assuming I can get 60K out of them and I rotate them every oil change 5K. What happens if a tire gets damaged beyond repair at say 30-40K, I didn't think it best to mix in an unused spare with 3 tires with 30 or 40K of wear. Then I'd just go to a 4 tire rotation till those 4 are worn out.
Oh, and to the original question, I cut and welded in extensions to the factory spare tire carrier.

 

I've got a 285/75/16 in my spare well

 

You can fit a 255/85r16 without rerouting the exhaust. Mine doesn't even come close, you just have to BFH the locating tabs properly.

 

That's the size of my trucks tires. Was this hard to fit up in there? I know this is an old post but maybe your still out there.