Alright, it's now time to order new tires for my beloved X-90. Stock tire size for these things is 195/65-15. When I got mine, Zig had installed 205/65-15's and they had seemingly extra room in the wheel wells.

My X-90 is currently running stock rims(which I think are 5.5" wide), 1-1/4" wheel spacers, a full Calmini 2" lift and a little trimming on the front bumper skin.

I want to run bigger tires on it. My favorite road tires happen to be BFG AT's but the smallest they come in is 215/75-15. General makes the Grabber AT2 in 205/75, 215/75 and even 225/70 for 15" rims. Doing some math based off my knowledge of tire sizing gives me these relative heighths:

195/65=126.75(stock)
205/65=133.25(Zig's)
205/75=153.75
215/75=161.25
225/70=157.50

By losing my wheel spacers, I know the tires will tuck better into the fenders, thereby allowing for a bigger size tire. Do you think that I can stuff the 225/70's on there and have them clear? Since these will be a custom order, I can't just go to the tire shop and try them, I have to figure it out ahead of time. And since these tires will be on there for a long time, I want to get something I like now rather than trying to "make do" if you know what I mean. By looking at the numbers above, it would appear that the 225/70's will fit better than the 215/75's. I wont be really flexing this thing out much, it mainly stays on smoother roads and dirt roads, logging roads, etc. Also the 225/70's are cheaper than the BFG 215/75's by over $20/tire.

It would appear that the 225/70's are something like an inch bigger than what Zig had on there, but I don't know if that is radius or diameter. I think it's radius. If that's the case, then the 225/70's are like an inch and a half bigger radius than stock and with the Calmini lift I should have room for up to 2" bigger radius than stock, right? Following that logic, I should have plenty of room for the 225/70's with 1/2 inch more clearance than stock/stock setups, right?

Anyone else have any thoughts on this? I could probably even whip up some coil spacers, like 5/8" up front and 1" rear to give me even more room if needed...

Well, searching around has brought me some new info about sizes:

195/65 has a width of 7.67, diameter of 24.98 radius of 12.49
205/65 has a width of 8.07, diameter of 25.49 radius of 12.74
215/75 has a width of 8.46, diameter of 27.69 radius of 13.84
225/70 has a width of 8.85, diameter of 27.40 radius of 13.70

So the 225/70's would be just over an inch wider than stock(just over 3/4" wider than Zig's), over all almost 2-1/2" taller than stock(just under 2" taller than zig's) with a radius of 1-1/4" bigger than stock(just under an inch bigger than Zig's). Sounds to me like they ought to fit pretty well, don't you think?

Digger,
Those are only one size larger than I ran with the stock suspension. They barely stay out of the fender at full compression (unless really twisted up) and only required a little trimming on the bumper. If you go much bigger than what you have you will need to start trimming. Without the wheel spacers you can get a little larger tire, but probably not a lot.

Your best bet is to do what I did, drive her off into a ditch (or use a jack if you prefer), twist up the suspension and start measuring. If I remember correctly, the tires that are currently on the X only had about an 1/2" of clear inside the wheel well without the spacers on. That will be you limiting width factor (if you take off the spacers) and your height limit will come from the front at full turn under compression. Be sure to check throughout full turn of the X. I swore the tires I had would fit fine, well they did at the fender and the wheel well, but barely clipped the bumper cover when turning under slight compression, so I had to do some slight trimming 

I ended up going with the shorter and wider tire along with the wheel spacers to get the wider looking stance. But you can go with a narrow taller tire if you remove the wheel spacers and measure your clearances.

Zig

So are you telling me that the 225/70's will fit without the spacers and I might need to do a little more trimming of the bumper cover? They are wider and taller than what you had on there. I figured I would have to pull the wheel spacers and probably trim the cover a little(keep in mind I'm running a stock, untrimmed cover now), but they should clear everywhere else, right? Maybe add short coil spacers and bumpstop extensions?

I'm not positive, I would definately flex it ouy and take some measurments before ordering the tires, there is not much room in those wheel wells without trimming.

Z

Well tonight I decided to go get new tires since I really couldn't wait much longer. The old ones were very worn. I also decided to go with the same thing Zig had put on there, size-wise since that made the speedo closer to accurate than the stock tires and the car seemed to handle very well with that size and I didn't want to kill my gas mileage.

Ok, so the stock size is 195/65-15 and I wanted 205/65-15. There were 205/65-15's on the car, Zig had installed them at his local Walmart. I went to my local Walmart and picked out some really nice looking Uniroyal Touring tires that had nice, deep tread and an 80k mile warranty. When they punched all my info into the computer, it said they couldn't put anything but the stock size on there. I explained that I had a 2 inch lift and that the car was wearing 205's from Walmart already and I just wanted to put the same size back on there, but it was no good, they wouldn't budge. The best they could do was mount them up to loose wheels and void the warranty. But that would have meant I would have to go home, put the x on jackstands and run the wheels back to walmart, which I wasn't about to do, especially if they were not gonna honor the warranty. I am VERY disappointed in Walmart! I tried to go to a different Walmart, but my name and all was already in their computer as well as a note saying I had just tried to get the tires earlier! I couldn't beleive it.

I ended up going to Pepboys and price matching Walmart's price for the tires and having them put them on. Plus they gave me a rebate for buying 3 to get one free and they are honoring the warranty! I have gone to Walmart for tires a few times in the past and every single time I have ended up not getting them there for one reason or another. You'd think I would have learned my lesson by now, huh? I will NEVER go to Walmart for tires ever again!

I ran into the same problem here to Digger, with more than my Tracker. I have a full sized chevy conversion van that's been running "235's" since I got it, wanted new tires on the rear and it took some talking but they did give in.. I'm done buying tires at WallyWorld also....