Upgrading to bigger tires

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Upgrading to bigger tires

Postby tklikely » Wed Mar 25, 2009 8:39 pm

I have an '05 Chevy 1500 Z71 crew cab. The stock tires are 265/70 R17. I am thinking about throwing 285's on there but have some concerns. Will this void my factory warranty? I know my speedometer might be off but how much? What about gear ratios, will it be hard on the transmission? I have looked on some other forums and some people say that 265 to 285 isn't a big enough jump to really change or affect anything and others say that you should update your gear ratios, speedometer, etc. What do you guys think?
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Re: Upgrading to bigger tires

Postby ajmorell » Wed Mar 25, 2009 8:45 pm

The difference between 265/70/17 and 285/70/17 is 1" in diameter (32" v. 33"). Your speedo will be off by 3.125% (33/32 - 1). Depending on your axle gear ratio and engine it will likely be fine, you might notice it a bit on the highway or towing a trailer, but probably not much around town. I wouldn't worry about gearing or anything with that small 1" jump in diameter, your speedometer will only be off by 2.1 mph @ 70 mph.
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Re: Upgrading to bigger tires

Postby Smackaduck » Thu Mar 26, 2009 7:14 am

Sounds like AJs got you covered. You may go to the dealership and see if they will reprogram you for your new tire size, most will with no trouble.
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Re: Upgrading to bigger tires

Postby tklikely » Thu Mar 26, 2009 7:37 am

Thanks guys. I didn't think it would be a big enough jump in size to really affect anything but I wanted to make sure. I'd hate to spend that money and have it f-up my truck. I just talked to the dealership and they said that could adjust the speedo but with only a 2 mph difference at 70, I may not worry about it....it may give me an excuse if I get pulled over. :thumbsup:
"Hey Griswold. Where do you think you're gonna put a tree that big?"
"Bend over and I'll show you."
"You've got a lot of nerve talking to me like that Griswold."
"I wasn't talking to you."
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Re: Upgrading to bigger tires

Postby ajmorell » Thu Mar 26, 2009 8:49 am

tklikely wrote:Thanks guys. I didn't think it would be a big enough jump in size to really affect anything but I wanted to make sure. I'd hate to spend that money and have it f-up my truck. I just talked to the dealership and they said that could adjust the speedo but with only a 2 mph difference at 70, I may not worry about it....it may give me an excuse if I get pulled over. :thumbsup:



The excuse card doesn't work.....I tried it :biggrin:
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Re: Upgrading to bigger tires

Postby Smackaduck » Fri Mar 27, 2009 5:45 pm

ajmorell wrote:
tklikely wrote:Thanks guys. I didn't think it would be a big enough jump in size to really affect anything but I wanted to make sure. I'd hate to spend that money and have it f-up my truck. I just talked to the dealership and they said that could adjust the speedo but with only a 2 mph difference at 70, I may not worry about it....it may give me an excuse if I get pulled over. :thumbsup:



The excuse card doesn't work.....I tried it :biggrin:


Me too, three times. Only got out of one of em. :lol3:
If they're dumb enough to be lured in by plastic you're really just doing them a favor.

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