max tire size?

i have a 1997 ford expedition 4x4 with a 3 inch suspension lift. i currently have 285 60r 18 nitto terra grapplers on it, would i be able to fit 305 60r 18 on it? i have a pic attached of the clearence i already have. i just want a little bit of a bigger tire look. thanks!

Well the only direction you really need to be concerned with is horizontally. They will fit height-wise i am sure, but you could run into problems with rubbing when turning at full lock. You can get spacers though that allow for more horizontal clearance.

Those tires are 12 inches wide that you have listed according to an online metric tire conversion calculator. Mine are 11.2 and are about as tight as it can get at full lock (that is also the width of your current tire), so you most certainly will need spacers in my opinion. Hope that helps. Here is the link for the tire converter.

http://www.xtremeterrain.com/tire-size-conversion-metric.aspx

I run 37s with a 3 inch suspension lift and 3 inch body lift. It rubs at full lock but hey if I can still make u turns.....its all good here

Gears would be the first thing i looked into before bigger tires

I have 315's with no rub after a bit of trimming on the lower valance.

camoford, how wide of a rim are you planning on running? This will drive a lot of what the "max" will be. I am running 37x12.5's with only a 4" suspension lift and you could probably get away with only a 3" suspension lift. But, to get this setup, there is a lot of very specific stuff you need to do. In short, you want the maximum tire, 8" rim is the only way to go. Going wide and you are going to have rubbing issues. TRUST ME!!!! Go narrower and you are going to be limited on how wide of a tire you can run, which is then going ot limit the size tire you can run. Also, 4.5" of backspacing is VITAL!!!!! When you are done, you are going to have less than 1/4" from tons of different things on your truck. If you want a little bit of breathing room, then 35x12.5's on an 8" rim will be your best choice.

If you are looking at more than 35" tires, be ready for some other mods. I managed to squeeze the 37's on to my truck with very minimal spent in fixing the other issues to make the tires work. But, you have to also ask yourself if you trust yourself enough to take a 3 pound hammer to the body of the truck? That is what it is going to take to go that big. Then you also have to trim some of the metal off of the bumper to make room there.

How big do you want to go and what are you willing to spend? You can run up to 35's on the stock 3.73 gears with no major issues (just have to limit how much you put in the back of the truck and can't be pulling any trailers over 5,000 pounds. If you have 3.55 gears, then I would say 34's are as big as you want to go. Now, this all goes away if you regear. But, that is roughly $1000 per axle.

If you need to know anything, let me know. I have been down this road before and I can tell you what will fit and what won't.

Hooch33 said:

Gears would be the first thing i looked into before bigger tires

Click to expand...

the only one running new gears is thermo. babysilk and walnuts both have stock gears in their trucks and 37s. but i know its on their list of things to do.

Trust me, if you are running bigger tires, gears make a world of a difference. I ran 35's for 6 years with the stock 3.73 gears. When I stepped up to 37's, I bit the bullet on the gears. Boy was I glad that I did. My mileage actually improved some even stepping up to bigger tires. I know it is a lot of money to outlay, but it is worth it. Should see peoples faces when I chirp the 37's.

just for what it's worth since no one else has posted it. just an info. statement;

the numbers for tires (285/60/18) refer to (width/height from rim to tread/rim size)
so you're asking about wider tires... here's what I know, I know that a wider tire doesn't ness. do better in snow than a less wide tire, and the turning radius of the truck is reduced considerably making tight turn parking impossible without a three pointer.

if you want to go taller stick with the 285 (which is unanimously agreed fits very well on these trucks) and go with a 65 or 70 series tire. the calculations are as follows: (appx.)

Specification Sidewall Radius Diameter Circumference Revs/Mile
285/60-18 6.7in 15.7in 31.5in 98.8in 641

Specification Sidewall Radius Diameter Circumference Revs/Mile
285/65-18 7.3in 16.3in 32.6in 102.4in 619

Specification Sidewall Radius Diameter Circumference Revs/Mile
285/70-18 7.9in 16.9in 33.7in 105.9in 598

then of course you get into your 35's and 37's,
35's aren't so bad to get into a set of (900-1500 or so new, mounted, balanced, tire dispblah blah) but suck @$$ to replace when you blow one whilst out playing again, and again, and again, and again.
now I'm poor so 37's aren't a consideration for me, a good used set of 285/65/17,18,20 sell online allllll day long for just a few hundred bucks.

now the 65 series tires are abundant so you have choice, BFG makes a 70 and a 75 series tire, looks pretty decent. so going to a 65 would net you half of an inch of lift.

not sure it does any good but it may help help someone else down the road reading through these posts.

I'm like many on here. I run 315/75/16's on a 8 inch rim with a 3 inch body lift, cranked torsion bars and 2 inch coil spacers in the back. No rubbing.