bigger tires
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Senior User
Joined: Oct 2009
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bigger tires
Im getting new tires for my truck next month and I was thinking of going 1-2 inches bigger than stock size. I heard that if you go bigger even by that much that it messes with your speedometer reading and your mpg. is this true? Im a complete n00b when it comes to wheels and tires.
Hotshot
Joined: Sep 2001
Posts: 11,958
Likes: 228
If your truck is a 2wd then get 31 10.50 15. Thats a great size. If its 4wd you can run 32 11.50 15.
The larger diameter tire will cause your speedometer to read slightly slower than your actually going, but not much, unless you have really large tires.
You can reprogram the PSOM if you have a 92-96. If its older you can change the speedo gear.
I didn't see it as that big of a deal with 31s, so I never reprogrammed my truck.
The larger diameter tire will cause your speedometer to read slightly slower than your actually going, but not much, unless you have really large tires.
You can reprogram the PSOM if you have a 92-96. If its older you can change the speedo gear.
I didn't see it as that big of a deal with 31s, so I never reprogrammed my truck.
Thread Starter
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Senior User
Joined: Oct 2009
Posts: 163
Likes: 0
If your truck is a 2wd then get 31 10.50 15. Thats a great size. If its 4wd you can run 32 11.50 15.
The larger diameter tire will cause your speedometer to read slightly slower than your actually going, but not much, unless you have really large tires.
You can reprogram the PSOM if you have a 92-96. If its older you can change the speedo gear.
I didn't see it as that big of a deal with 31s, so I never reprogrammed my truck.
The larger diameter tire will cause your speedometer to read slightly slower than your actually going, but not much, unless you have really large tires.
You can reprogram the PSOM if you have a 92-96. If its older you can change the speedo gear.
I didn't see it as that big of a deal with 31s, so I never reprogrammed my truck.
Hotshot
Joined: Sep 2001
Posts: 11,958
Likes: 228
I would say that 31s are a good fit. I have them on my truck. Even if my truck was 4wd it would probably have 31s too. The larger tires also can hurt performance since it effects the gear ratio. You speedometer will only be about 3 mph off at highway speed. Thats how mine is.
FTE Chapter Leader
Joined: May 2006
Posts: 11,273
Likes: 99
From: North Dakota
so, is it a 4x4, or a two wheeler? Here is my 94 sitting on 33x12.50r15s. Its all stock, with that said, I'm not running the tires yet, as I need to regear.. It is a huge turd with stock gears and 33s.
EDIT: I lied, I did trim the front bumper....
EDIT: I lied, I did trim the front bumper....
Posting Guru
Joined: May 2006
Posts: 2,486
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From: Iowa
Im running 33x12.50 and didnt modify anything. Runs good. Only rubs when hard over and just barley
also i have 3.55 gears, and the truck still has plenty of power. Its a 94 Reg cab 351w/e4od.
Gas mileage sucks though. Im thinking there something else wrong with the truck right now though. Thats probably more the reason for the bad Mpg
also i have 3.55 gears, and the truck still has plenty of power. Its a 94 Reg cab 351w/e4od.
Gas mileage sucks though. Im thinking there something else wrong with the truck right now though. Thats probably more the reason for the bad Mpg
FTE Chapter Leader
Joined: May 2006
Posts: 11,273
Likes: 99
From: North Dakota
BURNSTOUGHFORD, what wheels are you rinning? I have 15x10s with 3.75 inches of backspacing. wheel size and backspacing make a big differance too.
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Elder User
Joined: Mar 2004
Posts: 759
Likes: 1
From: mohave valley, arizona
i went with the 31/10:50 and im off about 5 mph on the speedometer but my gs mileage stayed the same, 15mpg
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Fleet Mechanic
Joined: Apr 2008
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From: Vancouver BC Canada
If you have the electronic odometer, adjusting for the tire change is easy and straightforward. Just takes a couple of minutes and you don't need tools. There is a how-to on here somewhere, do a search. If you don't recalibrate for the tire change, your mileage calculations will be off, unless you're using a gps or something. I went up to 31's with no complaints. Do recalibrate your speedo. It's fast and easy. The biggest driveability effect I've noticed is that it has lowered the revs on the motor, which is most noticeable to me when accelerating or passing on the highway. It's one reason why I'm contemplating a gear change, but for most users I don't think its that noticeable.
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