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Old 01-12-2016, 06:56 AM
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Tire questions

Want to upsize to 275/55 20. I have done some searches and seen different results. Those that have switched, any issues with abs light coming on and how much will speedo actually be off.
And, what are the little wing things got in front of the front wheels. Do you need them. Anyone take them off???


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Old 01-12-2016, 07:56 AM
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Re: Tire questions

I upsized to BFG AT KO2 - no ABS light. I had some rubbing on the rear passenger wheel well when I braked hard and if I hit a big bump. It was a non issue though because I added a lift and 1.5" spacers. Others have reported no issues at all so YMMV. My speedo is off about 3 MPH at 60 MPH. This is a good tool to show the difference in speedo:

https://tiresize.com/calculator/

As for the front wing things, I'm guessing you're referring to the little fascia pieces in front of each front wheel that hang down? I took them off, they're just held on by little pop tabs - easy enough to remove. I don't think they serve any purpose other than maybe helping with aerodynamics a little.
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Old 01-12-2016, 09:46 AM
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Re: Tire questions

If you upsize, don't forget you also need to upsize your spare to the same diameter as what's on the four corners. (4WD requirement) It doesn't have to be as wide, but it does have to match in total diameter.
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Old 01-12-2016, 03:13 PM
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Re: Tire questions

Quote:
Originally Posted by Jim_in_PA View Post
If you upsize, don't forget you also need to upsize your spare to the same diameter as what's on the four corners. (4WD requirement) It doesn't have to be as wide, but it does have to match in total diameter.
I've never understood why some think that a slight difference in tire radius is going to harm the drive train. Not trying to be a smart here. Maybe I'm just missing something.

Here's the way I see it. Lets say one tire has a radius that is 5% larger than the other. Then the rotational axle speed would have a 5% difference. So as far as the differential is concerned it would be the same as driving in a large diameter circle. I don't think that would harm anything if vehicle speeds weren't excessive. Additionally, my Limited has an open rear diff so there are no pressure plates would continually rub.

Now the center diff would also see differential in rotational speeds, but only half as much (2.5%). I'm not sure if that would be enough to harm the pressure plates in the center diff or not.

If anybody has better knowledge on this subject, I would be interested in learning.

I am planning on upsizing my tires soon but would like to keep the spare the same. As far as I am concerned, the spare is there only to get me to a tire shop

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