Skinny spare under LRA 12.5 aux tank (1 Viewer)

[nuclearbeef]

I have a 12.5 aux tank on order and I want to put the narrowest spare under the tank.
I asked in the wheel database thread if a 16" split rim take-off from a 79 series will fit and I got the answer that "no, it won't fit over the calipers.

1. Will it fit on the rear? (Could move rear to front and put spare on rear if front was flat)

B. Would most any 17" rim fit?

III. Universal spare is the skinniest thing I could find. Not really a match, but would get you to a tire shop, even from the trail. (I think)
Other options for pizza cutter spare?

20

Note: The 20 inch wheel comes in 2 variations. Part #25075-109 is needed for some large sedans, larger SUV’s, and some vehicles with large calipers like a Mercedes Benz with AMG wheels. Part #25085-119 is a 20” tire used for Porsche vehicles, high performance sports cars with larger calipers and...

ezsparewheel.com

 

[tbisaacs]

Just run a normal spare. @TeCKis300 has a 12.5 LRA and ran a 33 x 12.5” spare underneath.

 

[nuclearbeef]

Just run a normal spare. @TeCKis300 has a 12.5 LRA and ran a 33 x 12.5” spare underneath.

Certainly an option. The original spare fits; I was looking for improved ground clearance.

 

[nuclearbeef]

Like this.

Not mine. Pics are of a 100 with the 79 series split rim

 

[grinchy]

What size are the other four, then we can find something similar and skinny

 

[nuclearbeef]

OE: 285/60/18.

I believe they are 8", correct?
If so, 215mm is narrowest you can fit to an 8" rim?

I can't seem to find anything narrower than 8" with a 5x150 bolt pattern, except that universal donut spare I mentioned above.

I'm not doing any 5 tire rotations, so diameter is not important.

 

[grinchy]

a 235/70r18 is only 1.8% smaller - not many choices and the load range was only 110, but better probably than a donut
a 255/65r18 is only 1.3% smaller - lots of choices, 111 load range. probably what I'd go with if I had to.

I don't think 285 is going to drag for you though.

 

[grinchy]

Rim & Tire Size Calculator. Custom Offsets

Tire Tech Information - The Wheel Fitment, Tyre Stretch, Rolling Radius and Speedometer Error Calculator. Play with specs, try different settings, compare results

www.wheel-size.com

ignore wheel 2 - I was using the plus and minus tables . . . .

 

[grinchy]

There's a 235/80r17 with 120 load. +1.1%. It's the best option I see but has a 17" rim. So additional cost sourcing a 5x150 17" rim.

 

[TeCKis300]

Not the skinniest, but here's what a 275/65R20LT (34.1"x11"), looks like under the boot with an LRA 12.5 tank. It's about what stock is, or maybe just a hair lower.

I previously had a 305/55R20 (33.2"x12.3") and was not happy at how much lower it hung in the rear. I believe any of the smaller wheels or narrow tires should fit fine. Though not sure a 16" wheel can work for the 200-series front axle because of brakes.

 

[nuclearbeef]

Im not sure the cost/benefit is there if I can only save 50mm or so of rubber. Same 8" width rim is still under there.

Dragging less rubber is not worth the expense, I don't think. Although the rim might mount higher with less tire, I don't think it would be much.

I think I'd need to find some rim narrower than 8" with a 5x150 bolt pattern to make it worthwhile.

 

[nuclearbeef]

Not the skinniest, but here's what a 275/65R20LT (34.1"x11"), looks like under the boot with an LRA 12.5 tank. It's about what stock is, or maybe just a hair lower.

I previously had a 305/55R20 (33.2"x12.3") and was not happy at how much lower it hung in the rear. I believe any of the smaller wheels or narrow tires should fit fine. Though not sure a 16" wheel can work for the 200-series front axle because of brakes.

View attachment 2684187

Confirmed. The 16" Toyota split rims do NOT fit on the front or on the rear.

 

[WesSiler]

I hang a 275/70-18 Toyo ATIII LT under the 12.5ga tank on ours, and don't notice any difference in clearance. If you're really dragging the truck's ass that much, change to a heavier rear spring.

The idea of trying to safely get off a trail, or along miles and miles of highway until you can find a tire shop with a matching spare gives me jitters. A full-size spare should be considered more essential than any mods.

 

[nuclearbeef]

I hang a 275/70-18 Toyo ATIII LT under the 12.5ga tank on ours, and don't notice any difference in clearance. If you're really dragging the truck's ass that much, change to a heavier rear spring.

The idea of trying to safely get off a trail, or along miles and miles of highway until you can find a tire shop with a matching spare gives me jitters. A full-size spare should be considered more essential than any mods.

What started me thinking this way was the CHEAP and plentiful brand-new 79 series take-offs on the 16" split rim.
12 ply, or some such nonsense. WAY tougher than OE tires. They can (and do) cross the Kalahari.
But they don't fit over the calipers, so I'm just thinking about other options.

I'm not dragging at all yet. Truck is only 3 weeks old and I still have to wait a couple months for the tank to arrive from Australia. Just thinking ahead.

Anything narrow and tough that fits the axles. Diameter doesn't matter.

I know I've seen stuff about ruining your diffs with different size tires, but I could only see that being a real problem with clutch type LSD's, not open or Torsen-type.
Since we only have Torsen and open diffs, I figure it doesn't matter what diameter.
Again I would only use it for emergency; NOT for 5 wheel rotation.


I'll copy a letter from Torsen to a Mustang customer below:

From: Rick Barnes
Sent: Monday, January 04, 2016 5:15 AM
Subject: RE: 2015 Mustang GT with Torsen T2

Bob,

Thanks for your interest in Torsen. Although Ford does not package the Torsen together with an available minispare tire from the factory, we have been used in many applications with minispare tires elsewhere. In one particular application, the spare was about 25% smaller than the standard tire, so the 2” size difference that the Ford spare has should not be a problem. Assuming you stay within the limitations of the spare tire, you will not cause any damage to the Torsen differential.

Rick Barnes

JTEKT Torsen North America, Inc.
Rochester, NY
www.torsen.info/home.htm
585-464-5028

 

[TeCKis300]

I guess I don't see the value or cost savings in going for a particularly small spare. I'm with @WesSiler that a full performance spare has more utility.

As long as the tire is not hanging too low, it's not really impacting clearance or departure angle. The bumper skin, particularly the corners, are more likely limitations. Lift can also solve much of the clearance issues at the tire.

Even if the tire were to drag, I think that would be my preference over other parts like the muffler, bumper skin, etc. It's a tire after all, and can handle it. The structure above the tire is largely supported by the frame so it's almost designed to deal with any impacts.

As the LRA 12.5 does push things down by ~1", my compromise was to use 275/65R20LT (34.1"x11"). Versus my full size 35x12.5 tires. The 275 is still a full performance tire in every respect. Difference of 609 to 602 revs per mile, or about 1% diff. So no limitations to using center or rear locker in my setup.

The peace of mind to continue on a trip unimpeded should be the priority for a spare. Ideally matching, but matching diameter narrows still fulfills that mission.

 

[WesSiler]

The spare is not the limiting factor here. Not even close.

 

[nuclearbeef]

Thanks for the help guys!
Looks like I'll just keep my current spare wheel and see about a narrower tire for it.
5 tire rotation is out for me anyway since they don't give you an HE wheel for the spare.

My criteria were 1) Pizza cutter (for clearance)
B) Tough (at least as tough as the other 4)
III) Cheap

Only thing that fits the bill is the 79 split rim/tire. Perfect if I was driving a 100, but doesn't fit 200.

Oh, and BTW; I heard back from the company that makes the above referenced "universal" spare... It won't fit 5x150!

 

[Fisher23]

Personally .. I would not want to use that on the way out after I broke a perfectly good tire. Put that skinney one on, and then pop that.. better hope you are wheeling with people with good spare tires and not alone. I see your point but I would go 10" or 11" minimum. - skid plate it if you like is better than too skinny.

 

[nuclearbeef]

Personally .. I would not want to use that on the way out after I broke a perfectly good tire. Put that skinney one on, and then pop that.. better hope you are wheeling with people with good spare tires and not alone. I see your point but I would go 10" or 11" minimum. - skid plate it if you like is better than too skinny.

I assume that you are talking about the "universal" spare when you say you "wouldn't like to use that on the way out".

I agree, I wouldn't either. It would be quite the compromise. No matter, it doesn't fit.

The 7.5 x 16 Dunlops, on the other hand, would be tougher than the your remaining 3 tires.
Again, no matter. They don't fit either.

 

[nuclearbeef]

Update:

Got a nail in one of the OE Dunlops, so I put the spare tire on the HE rim and put a 245/75r18 on the spare rim. Hard size to find, but I found one used, but it still had nubs on the tread. Was probably a spare in its previous life.

Saves a good inch in ground clearance.