My speedo going 80....really....:-(

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Jun 3, 2010 | 02:55 PM

Aquik72

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My speedo going 80....really....:-(

Stupid question guys, I put some 18" rim and tires on my 09 SD, they are just a bit smaller in diameter than my factory 20's.

Question is, I know the smaller diameter tire will make the speedo appear that I'm going faster but is this racking up more millage as well.

Thanks in advanced !

Jun 3, 2010 | 03:07 PM

bpounds

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From: Whittier, CA

Yep !

Jun 3, 2010 | 03:09 PM

sammy77

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From: Illinois

Thats exactly what its gonna do...

Jun 3, 2010 | 04:44 PM

redford

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From: Stephensville WI

My speedo going 80?

Wow, I am thankful you're talking about your speedometer.

Jun 3, 2010 | 05:50 PM

sammy77

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From: Illinois

Quote:

Originally Posted by redford

Wow, I am thankful you're talking about your speedometer.

Man, thats not something I wanna see...

Jun 3, 2010 | 07:41 PM

M88

Mountain Pass

Joined: Dec 2009

Posts: 196

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From: Central NY

The winter tires for our 01 are 215 / 85 / 16 ... a bit smaller than the stock 265/75 tires. It's fun though, you can now go faster and not get in trouble!

Jun 3, 2010 | 11:34 PM

BillyBob69

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From: Wheatland, Mo

If you decrease the rim size, you need to increase the tire height. Otherwise you get what you described.

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Jun 7, 2010 | 08:34 AM

Aquik72

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That totally stinks, guess I have to go back to stock tires for summer vacation...ugh :-(

Jun 7, 2010 | 09:25 AM

#10

bpounds

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From: Whittier, CA

You don't have to. The difference is probably not that much, and it is easy to calculate. 5%? 10%? It is not that big of a deal if you plan to run the tires short term. If you plan to run them long term, your dealer can adjust the speedo for you. That will probably cost you $100. If you plan to switch back and forth between tires depending on the season, it is best to keep them approximately the same diameter.

(and no, I will NOT adjust your speedo for you, I don't care how tight it is)