Largest size spare tire fit in undermount carrier?

[RunnerRocks]

Thanks, I was able to get it in there but it’s a little crooked and leaning against the bracket.

I have Toyo AT3 E-rated LT275/70R18. When I just cranked it up fully tight, it would not fully seat.

While raising near the top, I need to wiggle rotate, then raise a little. Repeat until fully seated. It's fully seated and appears to the be the max size since it almost touches in the rear.

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[FourWalker]

Thanks, I’ll try that again. I was pulling on it to try to get it to seat properly. May need to air down a bit. Is that what you did?

I have Toyo AT3 E-rated LT275/70R18. When I just cranked it up fully tight, it would not fully seat.

While raising near the top, I need to wiggle rotate, then raise a little. Repeat until fully seated. It's fully seated and appears to the be the max size since it almost touches in the rear.

 

[RunnerRocks]

Thanks, I’ll try that again. I was pulling on it to try to get it to seat properly. May need to air down a bit. Is that what you did?

No air down. My tire tends to shift forward just enough to not seat in the forward brackets. The rubber sort of sticks to the brackets preventing it from fully seating.

By wiggling around while slowing lifting near the top, I could feel the tire move slightly rearward which permitted fully seating in the forward brackets.

 

[FourWalker]

Thanks, mine is actually getting caught on the rear bracket. Could be that there are slightly different tolerances car to car. I’m gonna go out and mess around with it again.

No air down. My tire tends to shift forward just enough to not seat in the forward brackets. The rubber sort of sticks to the brackets preventing it from fully seating.

By wiggling around while slowing lifting near the top, I could feel the tire move slightly rearward which permitted fully seating in the forward brackets.

 

[MPS2026]

I have an AT III 34x10.5 r17 mounted in the spare area of my SR5. Tight fit but no mods required. Actual diameter of this tire is listed as 33.5”.

 

[grey_4r]

Update:

The Toyo AT3's are 33.9" overall, might be a better fit.

That, plus upgrading the wheels would give me the sidewall increase, weight decrease, and potentially better bead grip. And obviously look cooler (most important, duh).

Did you every end up going with this setup? I am wondering if I can fit a 285/75r17 Toyo At3 in the spare location

 

[grey_4r]

I have an AT III 34x10.5 r17 mounted in the spare area of my SR5. Tight fit but no mods required. Actual diameter of this tire is listed as 33.5”.

Oh nice this is exactly what I am looking for, is it fully inflated? How do the D load tires compare to the stock tires?

 

[Van Solo]

Toyo Open Country AT3 285/75R17 Specs below:
PART #:355700

• LT285/75R17
• Overal Actual Diameter: 33.9"
• Overal Actual Width: 11.3"
• Approved Rim Width: 7.5" - 9.5"
• 10-Ply Rating
• Tread Depth (1/32): 16.5"
• Load (Lbs): 3195 @ 80 PSI
• Sidewall: Blackoff

Wheel Specs:
Blackhorn NS5
17x8.5 ET25

We will be fitting this tire underneath the TRD Off Road Hybrid in the next week (hope)

@rutsnext said The actual outside diameter of a BFGoodrich All-Terrain T/A KO3 in size LT285/70R18 is 33.7 inches when measured at its true inflated dimensions.

with 1/4" remaining i think we can make the 33.9" fit !?

wit calculations below 286/75r17 (To get the 33.9") acutal 285/75R17
0.5" estra sidewall let's do this!?

 

[3rdRunner]

Toyo Open Country AT3 285/75R17 Specs below:
PART #:355700

• LT285/75R17
• Overal Actual Diameter: 33.9"
• Overal Actual Width: 11.3"
• Approved Rim Width: 7.5" - 9.5"
• 10-Ply Rating
• Tread Depth (1/32): 16.5"
• Load (Lbs): 3195 @ 80 PSI
• Sidewall: Blackoff

Wheel Specs:
Blackhorn NS5
17x8.5 ET25

We will be fitting this tire underneath the TRD Off Road Hybrid in the next week (hope)

@rutsnext said The actual outside diameter of a BFGoodrich All-Terrain T/A KO3 in size LT285/70R18 is 33.7 inches when measured at its true inflated dimensions.

with 1/4" remaining i think we can make the 33.9" fit !?

wit calculations below 286/75r17 (To get the 33.9") acutal 285/75R17
0.5" estra sidewall let's do this!?

Your AT3 in a 285/75/R17 will fit.

 

[mfoga]

Your AT3 in a 285/75/R17 will fit.

Can you show a photo from Unser to show it’s sits in cradle since previous posts said you had to modify things.

 

[3rdRunner]

Unser? …under? I looked through my pics and I have nothing that shows the brackets. Don’t recall saying anything about modifications other than slight deflation- 40 Psi which I dropped to 33 to match the rest of the tires. It was definitely snug, but it fit. Only issue I had with this setup was dragging it on departure. The 285/75/17 AT3 is .6 inches wider than the stock SL but overall it is a great setup in terms of fit, ability to articulate, and ability to carry the spare.

 

[MPS2026]

Oh nice this is exactly what I am looking for, is it fully inflated? How do the D load tires compare to the stock tires?

It’s fully inflated. D load is fine. Stock tires were a softer ride but less capable off road. Trade off is worth it for my use. I attached a picture of the bracket that limits putting larger spare in.

 

[grey_4r]

It’s fully inflated. D load is fine. Stock tires were a softer ride but less capable off road. Trade off is worth it for my use. I attached a picture of the bracket that limits putting larger spare in.

Nice, thank you for sharing that. Definitely going to go with that setup. Did you really have to wedge it up there or did it fit without much force? Just curious what it would it would be like to take on and off if I needed.

 

[MPS2026]

No problem getting it under. Have to move it around some as you lift it up but should be easy. Attached is pic of spare against the hitch to give an idea of how much room you have.

 

[rutsnext]

Here's my take from everything posted, including my own experience. I'm thinking the profile of the actual tire you're installing is very relevant.

32.6" stock obviously fits fine. pic at front bracket attached for reference of how stock tire sits.
33.5" Toyo AT3 fits per MPS2026. photos shown in their posts above.
33.7" K03 fits with mod to front bracket - this is my setup with 285/70/18 K03. Pic of modified bracket attached.
33.9" Toyo AT3 285/75/17. Comments above make this an interesting one. A 33.9" would definitely not fit if the tire profile was like my K03. With a more square profile like the K03, the tire would hit low on the radius of the front bracket and not be sitting flush against the horizontal surface meant for the tire to be pulled up against. Maybe it works if the tire is rounder vs more square???

@Van Solo - maybe it's worth a check to see if the AT3 profile would allow it to fit?? Maybe the tire profile is different enough based on 3rdRunner's experience.

@3rdRunner - Would be great if you get a chance to post a pic of the tire at the front bracket (and maybe above) to give anyone else checking this thread as much real-world experience as possible.

I've included a pic to show my tire sitting flush/tight against the horizontal portion of the bracket. I'd want to make sure this was the case on any larger tire as I wouldn't want the tire only held against the radius of the front bracket.

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