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So ever since i mounted my 31 on my truck i notice my spare doesnt fit underneath and hits my panhard bar. So i was going to get a basket and mount it on to the roof but my friend says that on his xj he lost somewhere from 4-6 mpg with the tire mounted up there I was wondering if any of our members that have theres mounted on the roof have had any problems with this and can shed some light on this for me otherwise i will be spare less lol.

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I don't believe 4-6mpg, but certainly it's an abysmal influence on your CD. The larger concern IMO is that you're adding all that weight at the highest point of the vehicle. It would be one thing to do it as needed for an occasional trip when you know it's there. A little different when it's always there and you may have to make an emergency maneuver.

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So ever since i mounted my 31 on my truck i notice my spare doesnt fit underneath and hits my panhard bar. So i was going to get a basket and mount it on to the roof but my friend says that on his xj he lost somewhere from 4-6 mpg with the tire mounted up there I was wondering if any of our members that have theres mounted on the roof have had any problems with this and can shed some light on this for me otherwise i will be spare less lol.

 

Hi i am running on 32" (265/75) And relocating one of the spare tire brackets and trimming a little bit the rear fender the tire fits perfect without rubbing the panhard.

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I had two in the roof rack of mine for a few weeks on a road trip and there was a noticible drag and reduced milege down the highway, not sure it was as high as 4-6 but it was there and enough to make me take them off when I got home.

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Getting it on and off the roof rack is going to be a PITA. As ramdala said you should be able to fit the 31" in the spare location with a little bit of rearranging. I hear the rubber bumpers could be removed but I haven't looked into it myself.

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It kills the mpgs noticeably as stated above however not 4-6. You can also feel the drag when you let off the accelerator. I need to get mine off my roof someday and onto a rear bumper..... Never really found an issue throwing the spare up there, I just stand on the back tire and give it the ole' heave-ho!

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If you can lift 70lbs over your shoulder with one arm then you're a better man than I :)

 

Just test it with your current spare and see. But again, you shouldn't need to relocate a 31" tire with a bit of creative trimming. Now if you want to look 'cool' that's another story :sly:

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I had a 31x10.50R15 spare mounted in the stock location for 10 years without problems on my '97. You might just need to play with the orientation of the tire as you crank the chain to lift it into place. It seemed to fit into place better when the tire was angled so that it was higher against the bumper, and lower towards the axle, and then when it's cranked into position, the side of the tire closer to the axle would lift into place.

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Yeah, it can be a PITA to get a 33" on a steelie up and down, but I've been doing it for years now. I use both hands to prop it up above the rear window and then step on my back bumper and heave it up and in.

I usually have quite a few things up on my roof basket (shovel, axe, jerry cans...) and I've really only noticed a 1-2 mpg difference at most...but I drive like a grandma so take it for what it's worth.

I fit a 30.5" tire in the stock location and it was tight, so I always thought a 31.5 (or so) would actually fit but make it tight. If I could fit my 33, I'd much rather keep it down low for COG reasons as stated above.

Edited by Rick13
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My blazer has the spare on the roof (as did the 4runner it replaced), both in a 31" flavor on a factory aluminum wheel on the blazer. I'm sure it ain't helping MPG but I'd put money it's not 4mpg, even with other crap on the roof as well. It gets driven daily and has had no ill effects on handling (for the way my wife drives at least) though it gets some funny looks climbing up the side of the truck web doing tire pressure checks :lol: make sure it's good and secure when you mount it!

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I have my main spare on the swing out carrier at the back & a smaller (29.5") spare on the roof. I haven't noticed any drag or loss of mpg but I have so much crap on my roof rack I wouldn't have noticed anyway! :laugh:

 

Before anyone asks, I have 2 spares as I do a lot of desert exploring, miles from anywhere & guys in my group have gotten 2 or 3 flats before. :itsallgood:

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When i had my 31" spare on the roof, i noticed only a slight decrease in mpgs. What bothered me the most was wind noise and whenever i went over a decent bump it made noise. I'd check it every once in a while to make sure it was secure, and it was. Shook it back and forth, everything was tight. Maybe the weight of the tire flexed the rack a bit??? i still dont know.

 

I took the rack off months ago and just have the spare in the cargo area now...

 

Are you looking to buy a rack?

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I lose some mpg when my roof is on, -3 maybe. It doesn't affect too much when the spare on or not. High speed noise is even worse from my point of view.

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Have you considered trying other methods to carry your spare? There are hitch tire carriers that connect to your receiver, and fancier ones that pivot to allow the carrier to remain on while giving access to the lift gate. Only problem I see is if you happen to tow a trailer, but you might just throw that in the trailer for when you detach. Or for those with front mounted receivers....you get it. :)

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I was also concerned about this issue now that I got my 31"s, not really about whether the 31" spare would fit in the stock location or not, because I know it does, but if it was going to prevent me from being able to install a hitch, which is something I want to do ASAP.

 

That's why I think I decided to get a square hitch (Reese 51046), which looks like it would give me more clearance around the tire. I was initially going to get the round Reese 33050.

 

I like how the square hitches look anyways, and I was first concerned about the extra weight, but this one's only 6 pounds heavier thank the round model. $142 on Ebay. If you guys have more info on round hitches and 31" spares, maybe we'll erase any doubts.

 

Y.

Edited by yazir
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