Upgrade to 31x10.5, What changed?

[Charlie]

=D! And just to think.. without this forum.. I probably would have just gone with some Goodyear's in stock size... =\ I love the aggressive look these tires give my truck.

There should be a warning window when you enter the site

"Caution: This site will cause your wallet to magically lighten, and also, you will notice things wrong with your vehicle that need to be upgraded that you never noticed before."

 

[storlied]

Lmao, tell Rick that.. I think it should seriously be a warning.. That's priceless...

 

[madcatXR7]

Hey storlied, I never noticed the flowmaster SUV 50 in your sig, this is the muffler I've got picked out for my ride. How do you like it? Sound outside? Sound inside? I'd love to hear your feedback!

Congrats on the improvements to the rig. Bigger tires and more ride height just never get old, everyday I look at my truck and think, "SO MUCH BETTER!" I'm sure you'll be the same!

 

[smtcapecod]

I've got the Force II system on mine. I like it, I have it with the cats and its deeper but not too loud or resonant.

 

[storlied]

It's a future plan, from what others posted about it, including sound clips.. I like the sound.. no personal experience with it though... yet..

 

[storlied]

Did you guys look at your x's after 31's and did it look more compact to you? Idk, maybe it's just me.. looks smaller, more sport like.. lol
Could also be the raised white lettering.. =)

 

[Rolando920dy]

Will someone tell me why fuel economy would be worst when upgrading to 31's. Don't you get the same speed with less rpm's or more speed with the same rpm's?

 

[storlied]

I was wondering that also, my best guess would be weight, they also change your gear ratio. I have 3.73ls, with 31's they're as effective as 3.55's or so.

I've actually heard both answers to that question, it'll help mpg, and it won't.

 

[Rolando920dy]

I am also thinking of upgrading to 31's and am almost sure mine is 3.55, but one of my reasons to upgrade was the hope of better fuel ecenomy. After a couple of tanks let us know if you got better or worst mileage.

 

[storlied]

I don't have the money currently to even fill my tank up completely. =\!!

I'll tell ya though, the vehicle seems to handle a Lot better than before. Plus the increased height is awesome, specially when you pull up to another Explorer. Keep in mind with 3.55s, I imagine with 31's you'll be down to 3.27s and it might hurt fuel economy a lot. If I'm wrong, someone please correct me, this is just my understanding of it. You'll also notice a power loss, I did. But I don't worry too much about it, it's not too bad and once I'm up to speed I'm fine. Keep in mind, I also have the V8 which has a lot more torque than then V6.

 

[Charlie]

Your mileage will appear to go up, but it will actually go down. It will appear to go up, because you odometer will be spinning slightly faster than it actually should be. Because of that, it will look like you went 230 miles, whereas you actually went 220.

So, it goes down a little bit. I am not sure how much yet, though.

 

[storlied]

oh crap, i didnt think about the odometer..
but wait.. the speedometer is slower than actual speed.. so... wouldn't the odometer be slower?... iam so confused..
so would my truck be putting more miles or less miles on the odometer, considering the speedometer is slower than actual

 

[Charlie]

It's one of those weird things.

The speedometer will show that you are going 60, when realistically you are going 63.
Umm
I give up, I'm watching the packers vs seahawks, and this much thinking is just too hard for right now..

 

[storlied]

haha

 

[Rolando920dy]

Thanks for the info guys

 

[storlied]

What info, I'm still confused...

 

[hunterdan]

Your actual mileage may vary, but your perceived mileage will be lower than it actually is. Since your tires are larger than stock, they are going further per revolution than what the computer thinks. This causes your speedometer to read slower than you are actually going. Your mileage may actually be better than you think. You need to determine how far off your speedometer is, usually by a percent. Then multiply your distance by that percent. So if your speedometer is off by 4%, you multiply your distance traveled by 1.04 to get your actual distance. Then divide that by the gallons used.

Dan

 

[storlied]

What about the odometer?

 

[Charlie]

Well, the game is over, packers won.

Now, lets think this through.

If you show 60mph, you are going 63. So, for hour you drive, your odometer will show 60 miles, when you realistically went 63. So, if you burned 3 gallons of gas to go what the od shows as 60 miles, you are calculating you mileage and it is worse than it really is...

So, before, when I was running stock tires, I got approx 16mpg.
With the 31's, it is calculating out to about 12mpg.

However, neither calculation is accurate. The stock tires have the OD reading slightly more than real, and oversize tires have reading slightly less...

So, that means that my mileage has decreased slightly. But not 4mpg.

Also, I think it should all cancel out in the end to not really matter, because while in the city, with larger tires you will get worse mileage. However, on the freeway, I sit now at 1900rpm, as opposed to 2500ish with stock tires. So, while driving constant speeds on the freeway, I should be getting better mpg there..so, in theory, if you do city and freeway driving it should cancel out, and not matter.

**All opinions expressed above are me thinking randomly, and may or may not be true. All that I know is that the real MPG difference is negligible, so I am just going to pay at the pump whatever it takes, and forget about it. I am assuming you loose about 1mpg overall by switching to 31's.

After all, you are driving an explorer, so if this small change is bankrupting you, I think it is time to switch vehicles.

Edit: Wow, those last two posts were made while I was thinking/typing this one. My brain hurts now.

 

[Charlie]

Your actual mileage may vary, but your perceived mileage will be lower than it actually is. Since your tires are larger than stock, they are going further per revolution than what the computer thinks. This causes your speedometer to read slower than you are actually going. Your mileage may actually be better than you think. You need to determine how far off your speedometer is, usually by a percent. Then multiply your distance by that percent. So if your speedometer is off by 4%, you multiply your distance traveled by 1.04 to get your actual distance. Then divide that by the gallons used.

Dan

http://www.miata.net/garage/tirecalc.html

Use that. 31x10.50x15's are equivalent to 265x75x15's