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Posted: 12/16/2003 1:04:45 PM EDT
Hey lads. I'm thinking of putting bigger tires on my truck while keeping the stock rims. Nothing crazy, maybe 1 or 2 sizes taller and possibly 1 size wider. My question is how difficult is it to adjust the speedomoter? It's a late model truck with an analog speedo. Also, is there anything else I need to consider? Thanks!
Link Posted: 12/16/2003 1:10:31 PM EDT
Normally the speedo can be adjusted electronically. At some point it goes into the computer before it goes to the speedo, and thats where you make the change. Other things to consider: You may have to go for a lower axle gearing. Bigger tires suck up your power. Wider tires will most likely require new wheels to adjust the backspacing. What truck is it? What tires are you considering?
Link Posted: 12/16/2003 1:13:37 PM EDT
[Last Edit: 12/16/2003 1:14:34 PM EDT by cyanide]
Yes taller tires require a stiffer side wall, or you will be mushy going around corners and during quick maneuvers, like swerving to miss a object in the road. The speed may not need adjusted use a GPS and check your speed against that before you mess with having it adjusted as they can only be adjusted a certain number of times before you are not able to do it anymore.
Link Posted: 12/16/2003 1:13:48 PM EDT
If you keep it small the speedo wont be off more than a mite. Im runing 265/75 by 16, it came stock with 245. On a 15 inch rim where a 235 qould be the norm you may be able to go with 31X10.5. No need to adjust speedo. Lebrew
Link Posted: 12/16/2003 1:24:59 PM EDT
Be careful if you have a post 1998 vehicle. Not only do you need to correct the speedo but transmissions are also electronically controlled. And if the vehicle is drive by wire throttle, its even more of a problem. Since I don't know the specifics of the vehicle, it would be prudent to shop around for advise. On old trucks, its nothing more than changing the speedo input gear with the correct sized one. Or swapping the ring and pinion on the diff.
Link Posted: 12/16/2003 1:26:56 PM EDT
When you correct the speedo the transmission is corrected too. At least, my truck still shifts in all the right places.
Link Posted: 12/16/2003 1:34:02 PM EDT
Link Posted: 12/16/2003 1:51:04 PM EDT
Troy, Jack, Cyanide and everyone else - thanks for all the great info. What I'm dealing with is an '02 Explorer with 16" rims (stock). I was thinking of going to a 245 70R16 which isn't much bigger than what I already have. Possibly one size bigger than the 245 even. I'm not trying to make a huge statement, just something a bit bigger than what I have. The dealer showed me a set of Kelly Safari AWR tires that looked good. I would like to avoid re-gearing, etc if possible. Would this be necessary with the change I describe? Thanks again to everyone!
Link Posted: 12/16/2003 2:01:10 PM EDT
You can go up to 17" and not even bother with the speedo or odometer. Your speed and mileage will only be off a tad. LINK-- [url]http://www.tirerack.com/wheels/tech/plusone.htm[/url]
Link Posted: 12/16/2003 2:09:22 PM EDT
One size bigger on the same rim won't matter at all as long as you have enough clearance, especially on the steering axle. On a truck, this isn't usually a problem.
Link Posted: 12/16/2003 2:19:55 PM EDT
You don't need to regear. Going up one or two sizes will just make the SUV get up to speed slower. You can get your dealer to readjust your tranny/speedo at the same time. You might ask the same question at [url]http://www.ford-truck.com[/url] Here's a metric size converter to conver to inches. [url]http://www.jeeptech.com/javaAps/conv.html[/url]
Link Posted: 12/16/2003 2:22:34 PM EDT
Oh yeah, 235/70R16s = 28.9" x 9.25" 245/70R16s = 25.9" x 9.64" 255/70R16s = 30" x 10"
Link Posted: 12/16/2003 2:24:31 PM EDT
ITS WHEELS DAMNIT!!! The rim is the rolled edge that the tire actually seals against! Wheel 1. A circular frame turning about an axis; a rotating disk, whether solid, or a frame composed of an outer [RED]rim[/RED], spokes or radii, and a central hub or nave, in which is inserted the axle, -- used for supporting and conveying vehicles, in machinery, and for various purposes; as, the wheel of a wagon, of a locomotive, of a mill, of a watch, etc. Rim The usually curved or circular border or edge of an object. See Synonyms at border. The circular outer part of a [RED]wheel[/RED], furthest from the axle. A circular metal structure around which a wheel tire is fitted. This is my other pet peeve right after spelling lose "Loose"
Link Posted: 12/16/2003 2:32:54 PM EDT
I'm running 33s on stock gears, 3.55 The truck came with 29s. I replaced my speedo gear to the highest Dodge makes and the speedo is still about 10 MPH off. I was told it will cost at least around 1,500 to 2,000 bucks for the parts, kits and labor to regear my 4x4.
Link Posted: 12/16/2003 2:41:31 PM EDT
Originally Posted By tc6969: ITS WHEELS DAMNIT!!!
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You put your tires on a wheel and I'll put my tires on rim. Then I'll put the rim on a wheel.
Link Posted: 12/16/2003 3:17:23 PM EDT
A colleague of mine was killed because some punk put big wheels and tires on his POS truck. The extra strain caused the wheel to break free from the vehicle and it bounced right into her lap w/ over 100 mph of closing velocity (opposite side of freeway). She was on her way to bring food to her sick daughter. But hey, its a free country. Don't let the lack of a valid stress analysis stop you from modifying your truck. I mean it almost never happens right? Certainly following good design priciples is secondary to looking cool when your buzzing down the interstate in heavy traffic. May I suggest that you also take up smoking while refueling that fine vehicle?
Link Posted: 12/16/2003 3:28:19 PM EDT
Originally Posted By Weiseguy: A colleague of mine was killed because some punk put big wheels and tires on his POS truck. The extra strain caused the wheel to break free from the vehicle and it bounced right into her lap w/ over 100 mph of closing velocity (opposite side of freeway). She was on her way to bring food to her sick daughter. But hey, its a free country. Don't let the lack of a valid stress analysis stop you from modifying your truck. I mean it almost never happens right? Certainly following good design priciples is secondary to looking cool when your buzzing down the interstate in heavy traffic. May I suggest that you also take up smoking while refueling that fine vehicle?
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I've seen axles break with standard size wheels and tires. Mechanical things break. I had a tractor trailer smoke stack break off from a truck in front of me and pass right over the top of my vehicle, longways. I had no time to react and a foot lower and it would probably would have been my day to check out. On another note: I realize that the bleeding heart inside you wants to be protected from all that is bad but when you step out the door it might be your day. There are inherent risks in most everything.
Link Posted: 12/16/2003 3:34:50 PM EDT
Originally Posted By Weiseguy: A colleague of mine was killed because some punk put big wheels and tires on his POS truck. The extra strain caused the wheel to break free from the vehicle and it bounced right into her lap w/ over 100 mph of closing velocity (opposite side of freeway). She was on her way to bring food to her sick daughter. But hey, its a free country. Don't let the lack of a valid stress analysis stop you from modifying your truck. I mean it almost never happens right? Certainly following good design priciples is secondary to looking cool when your buzzing down the interstate in heavy traffic. May I suggest that you also take up smoking while refueling that fine vehicle?
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California, --------- figures.
Link Posted: 12/16/2003 7:10:10 PM EDT
If you run your little car straight under my big truck, I will walk away, and you will not. Does that make me a bad person? No. You do whats right by you. Look out for yourself, because no matter how much the liberals try, no one else is going to.
Link Posted: 12/16/2003 7:30:43 PM EDT
Originally Posted By tc6969: ITS WHEELS DAMNIT!!! The rim is the rolled edge that the tire actually seals against! Wheel 1. A circular frame turning about an axis; a rotating disk, whether solid, or a frame composed of an outer [RED]rim[/RED], spokes or radii, and a central hub or nave, in which is inserted the axle, -- used for supporting and conveying vehicles, in machinery, and for various purposes; as, the wheel of a wagon, of a locomotive, of a mill, of a watch, etc. Rim The usually curved or circular border or edge of an object. See Synonyms at border. The circular outer part of a [RED]wheel[/RED], furthest from the axle. A circular metal structure around which a wheel tire is fitted. This is my other pet peeve right after spelling lose "Loose"
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Calm down! Calm down! These aren't even truck tires. He just wants larger tires for his station wagon. [:D] Fred
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