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Doug

Larger tires

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I will soon be getting to the point of getting new tires on my truck.I have 17 x 8 rims and want to go up to a tire equal to a 33x12.5" .The p265's I now have now seem to be equal to 31 x 10.5".I will want to get the speedometer recalibrated.My question is does the computer need to be adjusted as well for shifting points or does the computer sense the loads and does it automatically as when you climb a hill and the transmission kicks down confused.gif

 

Thanks Doug M

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Doug ,I have some bad news for you I really dont have that answer for you, but the good news is I saved a bunch of money by switching to *ICO INS, no really check out (LINK TO COMMERCIAL SITE DELETED) compare makes different sizes vs there diameter, wear and tracton, I think it is a very imformative site HappyWave.gif

 

[ 02-27-2004, 01:40 AM: Message edited by: AMMODYTE ]

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Doug,

If I'm thinking correctly you should be able to change the speedo to read correclty unless it is a digital pickup unit. on the tire size difference you should be lossing one tooth on the spinner to make up the difference, the tranny will sense the load difference and should shift at the different points. Don't forget to change your brake lines over to braided lines makes a world of difference on stopping with the greater mass of the tire

mike

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I will soon be getting to the point of getting new tires on my truck.I have 17 x 8 rims and want to go up to a tire equal to a 33x12.5" .The p265's I now have now seem to be equal to 31 x 10.5".I will want to get the speedometer recalibrated.My question is does the computer need to be adjusted as well for shifting points or does the computer sense the loads and does it automatically as when you climb a hill and the transmission kicks down confused.gif

 

Thanks Doug M

 

There is ony a -3.5% difference in those two sizes. I dont think you will notice a difference. You'll find in most vehicles, the speedo is off about +5% when measured against GPS.

 

As far as regearing, I'm not sure of what rig you are driving. If your truck is underpowered to begin with, you may notice a lag while going uphill. Or if you have a weak drivetrain, the extra torque created by the size and weight of the tire could spell broken axles, diffs, and CV's. Larger tires can be a boon or burden.

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Ahhhhhhhh . . . but most of us sure do like em! biggrin.gif

 

AS do I, however auto engineers don't speed millions to design a truck with the intention of adding larger tires. There are very few trucks out there that have the hardware to handle it right out of the box. With the way things are going, larger tires will be a thing of the past with 99% of the trucks now being built IFS/IRS.

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Kneel, you're brandy new to the forum - just joined yesterday - welcome!

 

I thought the industry trend was for larger wheels and tires across the board. Cars are going 16, 17, 18 inches and trucks are heading about that. confused.gif

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Thanks for the welcome!

 

Larger WHEELS, yes. Tires have remained the same diameter, however the aspect ratio has been diminished. This is all fine and dandy to improve onroad performance, but take that same tire and wheel combo, air down, and play on the rocks. Say goodby to those shiny 17/18/20 inch alloys. This also applies to beach driving. Take a 265/75/16 and 265/70/17 and air down to 12 psi. you will have more sidewall flexed on the sand giving youbetter traction with the tire with the taller aspect ratio.

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