Tow vehicle tire size not to spec

Huntindog wrote:

davehultin wrote:
I'm looking to replace the tires on my tow vehicle (2010 Ford Expedition) and I was surprised to learn that my existing tires do NOT match the tires specs on the vehicle placard. I don't know when or why that happenend. Anyways...

Placard specs are P255/70R18
Existing tires are P265/70R18

So my existing tires are 10 cm wider than what's specified. Is that a bad thing? Or just a "thing?"

My Expedition is no champ for gas mileage, but does that extra 10 cm per tire take the mileage down significantly?It will reduce MPGS for sure, especially when towing

In your opinion, should I return to specs when I replace the tires, or is there a compelling reason to stick with the wider tires?

I gather you bought it used? If so, then the PO upsized the tires. It is a real popular thing to do on trucks.

You should be aware that a larger tire will reduce your tow rating. The factory rated it according to the factory size. While this is of little concern to those that do not tow, it could be for those that do. Just how much it will affect the rating is anybodys guess, But the fact that it WILL decrease the row rating is not subject to debate.

Since you tow, you likeley want all of the performance that you can get... That means put the factory size tires on it,

Technically true but for this situation, it's a small enough change to be largely irrelevant to the OP. The radius of the tire is only 0.7cm larger than stock.

This is an issue for guys with a jeep where they replace the stock tires that may be 24" outside diameter highway tread and upgrade them to something crazy like 36" outside diameter knobby balloon tires. These guys will see a big impact on MPG and tow capability.