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2006
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4,126 Posts
Discussion Starter · #1 ·
I have been running without a spare since i dont go out of Indy lately, but with the trip to carlisle coming I need to figure out what to do about carrying a spare.

I thought about throwing it in the cargo area, but really dont want to do that, so I think I want to put it on the roof.
I have a cargo basket, but it seemed to really affect my MPG so I removed it, but then I found a plastic air dam thing that I can attach to the front on the angled front part of the basket..I believe it is a Thule. I also have the alunminum crossbars that I could replace my factory crossbars with if needed.

My questions are---

does a tire on the roof affect MPG enough that I will noticed it on the 1100 mile round trip?

If i do mount it on the roof, do I mount directly to stock bars or aluminum bars or use the basket in combo with one of the sets of bars?

i am looking to not lose much MPG as the lift and tires will knock it down enough and I am not positive I can get my tune done beforehand.

Advice is appreciated.
 

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2004 gmc
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26,181 Posts
You will lose MPG, but nobody's done the exact numbers with a controlled experiment. You could do that for the rest of us.

Alternatively, throw it vertically on one side or the other of the cargo compartment - will be more accessible that way in case you need it.
 

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2008 gmc envoy_denali
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93 Posts
Whatever you do, don't use the stock crossbars... :nono:

Those things are so flimsy, I can't even keep my 50# cedar canoe strapped down good enough without looking like they'll snap. I have some aluminum ones on order.
 

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2005 chevy trailblazer_lt
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2,636 Posts
My questions are---

does a tire on the roof affect MPG enough that I will noticed it on the 1100 mile round trip?
Yes. I had mine mounted atop for a few trips, and it really was a killer on mileage. My best guess would be around 2mpg.

If i do mount it on the roof, do I mount directly to stock bars or aluminum bars or use the basket in combo with one of the sets of bars?
You want the tire as low as possible to reduce the air resistance. I had placed mine directly on the roof of the vehicle, then squeezed it with the factory load bars from infront and behind (no weight resting on the bars). Then I put two ratchet straps over that. Mine didn't budge during the time I had it mounted there.



i am looking to not lose much MPG as the lift and tires will knock it down enough and I am not positive I can get my tune done beforehand.
I haven't found the tune to do anything for my mileage, so don't depend on it to help. I drive fairly conservatively and I get about 15 mpg on the highway now (with the bumper, lift, roof rack, and all). It just comes with the territory.

If you want your best mileage, consider mounting it behind the vehicle, as I did, or inside. Anytime you increase your frontal area, it will certainly eat away fuel mileage.
 

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2003 gmc envoy_slt
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7,190 Posts
:iagree: It will hurt mileage and raise your center of gravity. However using the airfoil will help some. Semi's use them for a reason.:m2:
 
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