Ok... My 2010 FX4 has stock tires and rims ( 275/65r18).
Does anyone have a clue as to how High( or tall ) a tire I can put on the stock rim? Don't mind not going wider, but I'm ready for new tires, and I never liked the way the stock tires looked... Always looked way to small for the wheel well... I'm on a tight budget, so I want to keep the stock wheels, and NOT add anything to the suspension.
Thanks in advance guys!

 

you could probably run a 285/65R18 and not have any issues.

 

It kinda depends what brand tire you want to go with cause they vary a little in size from one manufacturer to another, but 286/65r18s will fit with no lift or trimming.

 

A 285 is wider, not higher... According to a guy at the tire rack, the first number is the width, the second is the height. So, according to him, a 285/65r18 is wider than a 275/65r18... Not higher.
A wider tire isnt going to look any different in the wheel well...

 

The first number is the width in millimeters, the second is the aspect ratio (not the height, this gives the height of one sidewall as a percentage of the total width of the tire), then the third is the size of the wheel in inches. To calculate the height, take the first number, multiply it by the second with a decimal in front, double it, multiply by .03937 (mm to in. conversion), then add the wheel size. I could explain that more, but it's out there on Google somewhere.

285 X .65 X 2.0 = 370.5 X .03937 = 14.5866 + 18 = 32.5866 (285/65/18)

275/60/18 = 30.9921, so 285/60/20 are a good bit taller.

If they make them, you can run something close to a 34" tall tire that is 275 mm wide on your 18" wheels without adding a level, but you WILL have to trim away part of the plastic inner fender liner. 275/65/20 wheels are 34.1" and would fit, but don't know the tire sizes for 18" wheels because I have 20's. Personally, I'd choose whatever is the closest to a 275/60/20, which is what I have, because they are 33.0" tall, but cost MUCH less (literally $100 less) than a 275/65/20 tire. Once you got above 33" or wider than 275 to 285, even in street tires, the cost jumps exponentially. I have BFG Rugged Terrains, which are technically an aggressive all-highway tire, but they look more like an all-terrain than a road tire and aren't noisy or expensive like a road tire. Mine were $210 a piece from Discount before a $100 rebate I got at the time, and tires for 18" wheels are a little cheaper than 20" ones

 

Thanks KMAC! Couldn't really ask for a better answer!

 

The 285x65x18 is about an inch taller then the stock 275x65x18's in addition to being wider. They'll fit at stock height on a 4x4 plus fill up the wheelwell's better. Heavier 10 ply tires so expect a drop in gas mileage.

 

That is not entirely true. The first number is the section number, or width, in this case 285 and I believe that is in CM. The second number is the aspect ratio, meaning a percentage of sidewall height as compared to the tread width. So a 285/65 WILL be taller, albeit slightly, than a 275/65.

For example. the BFGoodrich All Terrain TA KO in 285/65/18 is 11.5" wide on an 8.5" rim, and 32.7" diameter.

The same make and model tire, but in 275/65R18 measures 11.0" wide and 32.1" diameter.

 

No problem! I went though a similar issue when I got my wheels and tires, so I'm glad I could help. Let us know what you end up with or if you have any more questions

 

So would 285/70-18 fit without ANY modification?
If my math is right, they're 33.7

 

Without a leveling kit, I wouldn't recommend going over 33" at all. I have a 2.5" level with 35x12.5/17s and they just barely fit, I had to do some trimming to the plastic, and even grind down some of the metal flange at the back of the inner fenders.

 

Your math is correct but I'm not sure. I feel that they would fit without a level, but whether or not you'd have to trim some plastic up is up in the air. Either way, trimming the plastic is nothing to be afraid of and doesn't harm anything. My 275/60/20 (33.0") tires fit without rubbing or trimming of any kind on my 2wd while bone stock suspension wise and the wheels have a +20 offset, yours have something like +45, but yours is also much higher off the ground. I don't mean to confuse you by adding in another variable there, but I say go for it. Worst case scenario you'll have to cut some plastic that you didn't even know was there.

The biggest thing is that the tires you'll be looking at don't have big mud terrain side lugs and they're narrow, both of which make all the difference.

 

I have the LT275/70R18 BFG AT KO's which are actually 33.2" tall and 11" wide according to BFG's website. I have a 4x4 with a 2" level and no rubbing issues whatsoever.

 

Thanks guys!