The change in overall diameter is +/- 1.1" larger. You would have .55" more tire forward, and .55" more tire to the rear when steering full lock.

Go to the truck and when parked turn the wheels in each direction and then have a look. Do you see at least 3/4" clearance fore/aft, now? That's how much extra room you would need to fit the new tire size, allowing for control arm bushing deflection when reversing, etc... stuff up there moves around a bit even when everything's new. Good luck.

 

Thanks. That helps. I’ll give that a look today. Much appreciated.

 

I checked this out. I currently have two fingers (1-3/4”) at the closest contact between the wheel and front crash bar, or plastic I don’t recall at the moment. Either way, more than the .55” from 275/65 to 275/70. But my tires don’t have much tread left so I’m thinking it might actually be a 1” increase after accounting for new tread. Still should give me 3/4” of clearance, give or take. Now I wonder what that would look like without leveling the truck? Ford dealer told me I can go up one size no issues. Another concern is the only way I get a 275/70 is to go from P to LT which will probably give a harder ride. Any thoughts/suggestions would be appreciated.

 

you will get a harder ride with lt tires but if you look for tires with a c or d load rating it'll be softer than an e or f. Also you can run a 285/70r18 stock height with no rubbing.

 

Thanks. 285/70 is 34”, that would fit without a level? The new Falken A/T4W in 285 is actually a C load but a whopping 69#. That’s 29# more than my current tires. MPG aside, wondering what that would do to my suspension, power, and 3.55 trans?

 

I ran a 285/60r20, which has the same dimensions as a 285/70r18, toyo mt with no level with no rubbing anywhere. That does sound extremely heavy but I can't same I'm surprised since most falkens are. Might want to see if Goodyear has something a little lighter. You will notice a little power loss but I've found that rolling resistance matters more than weight in power and efficiency. Your suspension can take it but when your shocks are done I would recommend bilsteins or fox depending on your towing needs. I'm trying out eibachs at the moment and I'm not sure I'm sold on them yet.

 

That’s good to know. Toyo A/T3 in the same 285/70/18 is only 56#. So Falkens are heavy. Not as many choices in the 285/70 for some reason. And I have to stay with the 70 sidewall if I want to step up a size or two because anything less won’t fit my stock 7.5 rims. Can’t afford rims too. Good info, thanks.

 

A 285/70 or a P285-70 will always be of lighter construction than any LT285-70 in any wheel diameter (say, from 16" to 20")


For example, I ran on my truck a 285/70-17 Firestone Destination A/T2 that weighs 43 lbs but wanted a perhaps more-durable sidewall as insurance (it isn't much because all tires sidewalls are vulnerable to damage) when travelling far off highway, PLUS I wanted a taller, narrower tire so I switched to a new size offered by Toyo: a 34X10.50XR17LT D Load Range that weighs 55 lbs. My wheels weigh 26 lbs, so the total flywheel mass is 81-ish lbs.

The rolling resistance may be the same as I have noticed my shift points remain the same (not having to tip any deeper into the throttle) but I notice a slightly higher brake pedal effort to slow a taller tire since I will assume the taller tire is imparting a greater leverage against the brake (as well as it's additional 12 lbs rotating mass).

 

A 285/65r18 fits stock size wheels no problem with barely any lift on the edges of the tread.

 

I can’t find any P285/70/18, everything is LT. I would prefer a P tire because I really don’t do much off road stuff at all. I’ve kinda gotten used to the softer ride of a P tire. The C and D tires are few and far between as well, at least in the brands I’m looking at. Everything is E when you get to the bigger sizes. Except for the few 285 and up with a 60 or 65 aspect. And the book says I need at minimum an 8” rim for those. I have 7.5.

I think I’d get used to the loss of mileage and little bit of quickness with the heavier/taller tire. So long as I don’t go up too much. I put LT’s on an ‘86 F150 years ago and after awhile I didn’t even notice the extra weight. Good information, thanks.