Upsizing tire sidewalls (40 to 45) - advice or experiences

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NautiOne

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I currently have 265/40/R21 tires on my 2020 Nautilus and am considering upsizing the tires (for sidewalls only) to 45 aspect ratio (265/45/R21) to make the ride even more comfortable. Has anyone done this? Any advice? I do realize that the speedo will display a slightly lower speed than actual.
 

bbf2530

Junior Member
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I currently have 265/40/R21 tires on my 2020 Nautilus and am considering upsizing the tires (for sidewalls only) to 45 aspect ratio (265/45/R21) to make the ride even more comfortable. Has anyone done this? Any advice? I do realize that the speedo will display a slightly lower speed than actual.

Hi NautiOne. The 265/45-21 tires will fit. And as you stated, the speedometer will be slightly off. You will be going slightly faster than it reads. And the odometer will also be slightly off. Not enough to worry about in either case.

On a related note: Not sure how worn your current tires are and what you are expecting as far as a ride improvement. Apples to apples with tires, there will be some ride improvement, but it won't be significant. Certainly not worth the cost if you do not actually need new tires yet.
Therefore, I would recommend getting the full life out of the tires you have, then spending the money to make the switch.

Good luck with whatever you decide to do.
 

NautiOne

New member
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Arkansas
Thanks for the input bbf2530! Currently have the Conti CrossContact LX Sport w/ 27K miles. There is still 6-7 /32s remaining. Reviews on these are not great, but I have no complaints.
 

bbf2530

Junior Member
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Thanks for the input bbf2530! Currently have the Conti CrossContact LX Sport w/ 27K miles. There is still 6-7 /32s remaining. Reviews on these are not great, but I have no complaints.

Hi NautiOne. If you are happy with them, that is all that matters and ignore the "reviews".

EDIT - Most new passenger car tires come with 10/32 - 12/32 of tread. And the last 2/32 - 3/32 of tread is end of life. They should certainly be replaced by the time we are down to 3/32. And the wear bars are at 2/32.

So you still have a minimum of ~2/32 - 3/32nds of tread life left, according to whether you live in a cold/snow prone area or not. That is calculating with a 4/32 absolute minimum usable tread life. It is not advisable to keep tires with less than 4/32 of tread, unless you only drive in a very dry, no snow climate. In other words, the low desert...lol

Of course, then there are the tire age and other limits that come into play as to when tires should be replaced, no matter how much tread. But that is another story. ;)

Let us know how you make out and good luck.
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