I have a Platinum with the stock 20" rims. Recently I added a 2" leveling kit.
What tire sizes are compatible without messing with the 4WD and the computer settings?

 

Based on my experience after putting 275/65/20 (34") tires on the stock 20's when I replaced the stock 275/55/20 (32") tires, the only size tire that won't mess with the computer settings are tires that same overall diameter as what came from the factory. Obviously bigger tires change your speedo reading, but I figured there was nothing I could do about it and was just going to leave things be. a little later on, I learned on here that because I had gone to a tire with the same size overall diameter as one of the factory tire size options, in this case the stock raptor tires, that it was a quick easy reprogram from 32's to 34's and I would be on my way. So I went down to the dealer and dropped the truck off for an oil change and a speedo reprogram, I get back and they tell me it can't be done because all the trucks only have the settings for the stock tire sizes in their trim line available.

 

Thanks for the info. So what changes did you experience?

I thought about 285/55/20 but not many tires are available.

I don't need an off-road tire. But still need good traction in the snow.

 

Ok guys help me out here. Am I better off staying with the stock size? I am good with the 55 walls but want something wider.
Do not want the messed up speed and computer, nav though.

 

I saw the usual and expected changes with stepping up to oversized tires. I don't have a level or lift on my truck so when I'm turning and have the steering wheel all the way to the left or right, the tires rub on the plastic on the back of the bumper. If I back off by even less than a 1/4 turn they don't rub. I've kept an eye on it and haven't seen any noticeable wear where it rubs. My speedo is off, by 4 mph at 65, and the mpg calculator on the screen is off vs what I am actually getting. the truck still thinks the tires are the stock size and calculates it's distance off the revolutions per mile of that size tire so it thinks I've traveled a shorter distance than I have. according to the mpg calculator on the screen I get about 14-14.5 average mpg over the life time of a full tank since I swapped tires which is worse than with the stock tires by about 1-1.5 mpg . But if I hand calculate the mileage then the mpg change isn't as drastic. the formula I found online to check how far your odometer is off and calculate mpg using oversized tires, is : old tire diameter / new tire diameter and then take that number subtract it from one and the difference is the %age of how far off your odometer is.

so in my case I would take 32/34 =.94 1-.94 =.06 so my odometer is off by 6%
I can now take that 6% and use it to calculate my real mpg

for example today, I filled up with 33 gallons, the truck said I drove 472 miles and averaged 14.3 mpg. I know my odometer is off by 6%, so my real mileage is going to be 106% of what the truck says. So I multiply my mileage x1.06, 1.06x472 =500.3/ by the 33 gallons I filled up with =15.1 actual mpg

So i'm actually getting about the same mpg I was before swapped to the bigger tires.


When I changed tire sizes, I only did so because I wanted to switch from a p rated tire to an LT rated tire with a 10 ply or E rating on them because of all the hauling and towing I was doing. I looked at all my options size wise to get that rating and came down to either a 285/55/20 or a 275/65/20. When it came to picking tires, I had narrowed my choices down to either Toyo A/T II's or Michelin LTX M/S II's before I even started picking sizes just based on personal experience with both tires. My dad ran michelin ltx's exclusively on three different trucks for almost 15 years and they were great. They're 65k tires and they seemed to last all of that every time. Everyone at the company I work for runs the toyos on their trucks and swears by the them plus they have an account at les schwab so I got a discount. I ended up picking the toyos and I went with the 275/65/20 over the 285/55/20 because it was $50 more per tire for the 285. The michelin m/s2 only comes in the 275/65/20 but they have both the 275 and 285 in the AT2 but the 285 is $60 more than either of the 275's are.

I personally would recommend either tire to anyone out there in the market looking for new tires but since you mentioned not needing an off road tire but still wanting something that is good in the snow, I would tell you to give the michelin m/s2 a look

 

Thank you for your answer, bigblueknight. I had the Michelins on my Expedition and loved them.
I just hoped Ford could adjust the diameter so there was none of only a slight difference. I am afraid the navigation will be off when it calculates the distances.

 

Go with 33's. The 1" difference in diameter will only make a slight difference with the speedometer vs. the stock 32's. The stock size will look too small with a leveling kit.

 

A little bit after I got the new tires (september 2014), the gps started acting funny. I would pull up the nav screen and it would show me driving on the side of the road about a block over from the road I was on. I found a fix for the issue on here, disconnect the battery for about an hour and do a master reset on the sync system. I haven't had any problems with it since until the other day when it did the same thing. I didn't do anything to it and it went away. I think both times it probably had something to do with the heat and truck sitting out in the sun. It was 106 the other day when the gps was acting up and the truck had sat out in the sun all day. I think when you first start out on a route the gps may rely on tire size and steering for change of direction but once you get going i think the antenna takes over

 

Go here to get tire size calculations: Tire Size Calculator - Tire & Wheel Plus Sizing.
An inch can make a difference.

To get your computer set correctly, go to the dealer. It will cost. And hope they get the revs per mile right. There are factors like tire squish that throw off a simple circumference into mile calculation.

I don't know what my dealer was using but the mph and mpg were off.
BTW on my truck 18" rims were stock. There was a upgrade charge for 20" rims. My spare is also an 18" rim. The dealer told me they had put an 18" wheel as a spare because it fit in the space for the spare. What a load of BS. The spare which is a 275/65/R18 is the same diameter as the 275/55/R20.

Also, You have a 4x4. If for some reason, you have to use your spare for any length of time, it should be the same size as the other wheels/tires on the ground.I was having a problem with harsh downshifting while in stop 'n go traffic. I would get up to speed where the trans would shift into 3rd. I would slow down to almost a stop and when accelerating again, the trans would stay in 3rd and downshift to 1st with a noticeable rough shift. There was a TCM upgrade for it. The service foreman told me that the change in tires without a TCM adjustment would compound the problem.

Go to the 1010tires.com site and compare your old tire size with a new one and look at the changes.

 

I went with 275/60/20 with no level and have no issues.

 

I come here for a lot of info, but I rarely post. It looks like you're kinda in the same boat I'm in. You'd like to go wider not necessarily taller so as not to impact speedo and gps... This is a pretty good calculator Tire Size Calculator and if I'm reading it correctly, a 305/50/20 is just over an inch wider with negligible change in diameter. I hope I helped.

 

I went with Toyo OC AT2 275/65R/20 tires and a 1-1/2" Autospring Level on the front only. Still keeps some rake to the front of the truck. I could have ran the tires on stock wheels without the level, but after the tires I decided to add the level. Installed on a 13 Platinum 4x4, I have to say, it's more enjoyable to drive now! As far as the ride, it is somewhat firmer with the LT "E" rated tires, but I run them at 38PSI, and that helps.

 

Any chance you have some pictures of the truck on the 275/65/20 AT2s? That's the size and tire I'm considering for my '13 Platinum as well. Would love to see your setup.

 

I have Mickey Thompson 275/65/20's on my factory wheels with the same set-up you have, it didn't help the gas mileage but then again it ain't a Pruis!

 

You know I am hearing that line about it not being a Prius more these days and honestly it makes no sense to me. Although you bought a truck, the simple fact of losing gas milage simply by putting on different tires is something that people like myself are trying not to do. The reason for me is that I commute in my truck and want to get the best milage I can possibly get all the time. Putting on new tires and losing 2 mpg sucks.