Going up in tires size just a little

Mike20089

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Ok so I’m wanting to go to a 265/70r17 bfg ko2 My truck is a 2021 ranger fx4 stock. I was told that it won’t rub but would affect my speedometer and my mileage would be off?? Is this true if so can’t the dealership just program it? Anyone of you guys been through this? Thanks.
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got3fords

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Ok so I’m wanting to go to a 265/70r17 bfg ko2 My truck is a 2021 ranger fx4 stock. I was told that it won’t rub but would affect my speedometer and my mileage would be off?? Is this true if so can’t the dealership just program it? Anyone of you guys been through this? Thanks.
Just curious what size you are running now?
 
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Your speedo will be off a good amount, which will throw everything else off.

I went to the same size but in a Goodyear Duratrac, and my speedo was off by a good 5 mph or so at 60. This can be adjusted with a tuning device if you already have one, otherwise you'll need to plug in your laptop to the truck and adjust in with Forscan. It'll still require some adjustments as you'll want to check it against a GPS if you can. There are a few different posts on here that explain how to do it, I've made a post on how to do the math to zero in the adjustment number. Just look at my post history.
 
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Mike20089

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Your speedo will be off a good amount, which will throw everything else off.

I went to the same size but in a Goodyear Duratrac, and my speedo was off by a good 5 mph or so at 60. This can be adjusted with a tuning device if you already have one, otherwise you'll need to plug in your laptop to the truck and adjust in with Forscan. It'll still require some adjustments as you'll want to check it against a GPS if you can. There are a few different posts on here that explain how to do it, I've made a post on how to do the math to zero in the adjustment number. Just look at my post history.
Ok thanks. Doing that won’t affect the warranty at all?
 
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Ok so I’m wanting to go to a 265/70r17 bfg ko2 My truck is a 2021 ranger fx4 stock. I was told that it won’t rub but would affect my speedometer and my mileage would be off?? Is this true if so can’t the dealership just program it? Anyone of you guys been through this? Thanks.
If your sizes are correct old tire 265/65/17 new tire 270/70/17 the difference is 30.6 x 31.6 with that size change you should only be off a mile or two. I put on 285/65/18 KO2 which are 32.6 and I was only off about 3 or 4 miles at around 65mph. Easy change in Forscan just takes a couple of tries to get it right.
 
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You’re going up in size, not much but enough to make a difference

The recorded mileage will be lower, which will calculate poorer gas mileage than what is actually occurring. Your dealer can re-calibrate your speedometer but they have a limit as to how much - the new tires should be within spec for them. Their setting will be close but might not be exact. Expect to pay, unless you bought the tires from them and they’re doing the install, balance, etc. Then, they might do it no charge.

Like others have said, you can do it in Forscan and tweak it until it’s perfect, if you have it or by using your aftermarket tune, if you have one and it has that feature.
 
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Mike20089

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If your sizes are correct old tire 265/65/17 new tire 270/65/17 the difference is only 30.6 x 30.8 with such a slight size change you should only be off less then 1 mph at most. I put on 285/65/18 KO2 which are 32.6 and I was only off about 3 or 4 miles at around 65mph. Easy change in Forscan just takes a couple of tries to get it right.
I think it comes out to
 
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Mike20089

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I think it comes out to 31.6 30.6
 

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put it to you this way...when you buy a brand new set of tires, the tread is at it maximum (usually 9mm deep).....as you wear them out, the tread disappears. up to 14mm of tread depth gone. About half an inch.


do we all adjust our speedos as we wear out our tires? no, because that's a little too OCD for even the weirdest ones out there.

but heres a comparison for you to see if you can live with the numbers.

1642110341507.png
 

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If your sizes are correct old tire 265/65/17 new tire 270/65/17 the difference is only 30.6 x 30.8 with such a slight size change you should only be off less then 1 mph at most. I put on 285/65/18 KO2 which are 32.6 and I was only off about 3 or 4 miles at around 65mph. Easy change in Forscan just takes a couple of tries to get it right.
You got that tire on stock without problems?
 

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Ok so I’m wanting to go to a 265/70r17 bfg ko2 My truck is a 2021 ranger fx4 stock. I was told that it won’t rub but would affect my speedometer and my mileage would be off?? Is this true if so can’t the dealership just program it? Anyone of you guys been through this? Thanks.
i put on 2657017 bfgko2 load e bone stock no issues with rubbing and i use my truck like a truck and its off pavement on a regular basis. The speedo will be off, but not by a crazy amount. it is very simple to fix in forscan or with a tuner that allows gear / tire size or revs per mile changes. takes like 5 mins with the ford perf tuner. a dealer could change it for you but they may charge more than it is worth or give you a hassle.
 
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