Different size winter tires

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Apr 6, 2012 | 08:39 AM

seville009

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Different size winter tires

Looking at a 2012 F-350 with 20" tires. I have a 2006 F-350 that I have dedicated winter and summer tires, but they are 18". I also already have chains for an 18" tire and would not want to buy new ones for the 20" tires.

Would there be any problem with putting my current 18" tires on for the winter? Would I have to have the speedometer recalibrated each year when I switch between the 18" winter tires and 20" summer tires?

I have the same question relative to a car that a relative just purchased - a 2013 Ford Edge. It came with 20" tires and they want to get dedicated winter tires when the time comes, but the selection and cost for the 20" winter tires is pretty high. Can they get 18" tires for the winter and switch back and forth between the 18" and 20" without having to do anything else (no recalibration)?

Thanks.

Apr 6, 2012 | 09:43 AM

kd0axs

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From: Nowthen, MN

You don't need to worry about rim diameter so much as overall tire diameter. As long as both sets of tires have the same (or very close) diameter, it won't be necessary to recalibrate.

Apr 6, 2012 | 12:05 PM

seville009

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Thanks.

I guess my issue/question is how much can I deviate from the original tire.

On the 2013 Ford Edge, for example, the existing tire is 245/50R20. If I just change it to 245/50R18, would that cause any issue with recalibration since I didn't change the width or aspect ratio? Could I go to 245/60R18 without any problems or modifications?

Thanks again.

Apr 6, 2012 | 12:53 PM

PA-Mark

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From: Mt. Holly Springs, PA

If its only for two to three months its not worth recalibrating in my opinion, i bet you will be less than 5 mph off. On my f250, i went from 30" tall tires to 35" tires and my spedo is only off 4 mph.

I bet you have more problems with TPMS than the speed-ooooo

Apr 6, 2012 | 01:57 PM

seville009

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Got it...thanks for the response.

Apr 6, 2012 | 02:18 PM

kd0axs

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From: Nowthen, MN

Quote:

Originally Posted by seville009

245/60/18 would be about perfect.

245/50/20 comes out to a diameter of 29.65" and 245/60/18 comes out to 29.57". Can't get much closer than that. A tire's diameter will change more than that over its life just due to tread wear.

245/50/18 would be 2" smaller in diameter than the 245/50/20 since it has the same width and aspect ratio on a 2" smaller wheel.

Apr 6, 2012 | 04:14 PM

Lou Braun

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From: West Cornwall, CT

Your '06 tires/rims probably do not have the TPMS system that the newer trucks have. This means that the warning light will be lit all winter long. Adding TPMS sensors to the '06 rims would fix this.

As long as the tire height is the same (or close) between the 18 and 20 inch tires, no recalibration would be needed.

Lou Braun