Hi,

I bought my 2008 Expedition used with the intention of using it to get to the tops of mountains where I hang glide from. The problem I'm seeing before I even take it up a mountain is that the tires it came with are total street tires, and kind of low profile or something. NOT aggressive by any means whatsoever. I have to tell you that tires and sizing has always been something that's confused me, so that's why I'm here. Currently I have 275/55 R20 and would like to put on something that increases ground clearance as much as possible and is a bit more aggressive for 4WD roads, but how big can I go without having any rubbing or whatever? Maybe if someone can help me with sizing, I can pick out something that meets my other needs. Thank you in advance!

 

Anyone?

 

Maybe someone can point me in the right direction?

 

My 07 Expy came stock with 265/70/17 and it's 2wd so I'm not 100% sure if we have the same clearance... but I was able to fit 285/70/17 with plenty of room.

The first number is the tire width (in mm), the second number is a percentage of the first number, and it represents the sidewall height. In my case, that would be 285mm wide, and 285x0.7mm sidewall height. And obviously the last number is rim size.

So I ended up going from about a 31.6" tire to a 32.7" tire just by changing the width of the tire. I would bet you could fit a 285/60/20 under yours, but I don't think I'd try for much more without a lift or leveling kit.

Here's a cool calculator I found that helped.
https://www.tacomaworld.com/tirecalc

Here's mine with the 285s.


07 Expy 285/70/17


Good luck!

 

Thank you so much for taking the time to reply! Much appreciation from California.

 

Sure thing. Hope it goes well!

 

Now I'm thinking I might want to swap out my rims, ditch the 20"s that came with it and get something smaller with more tire.
How does one figure out the max tire size given a specific rim size? Yours looks good with the sizes you have.

Anyone else on here have thoughts?

 

Thanks! You can use that calculator and just change the rim size and compare it to the original size. Just got around with common tire sizes. I'm not sure what rim size you're planning on but if you want 17s, you can start with 285/70/17 or if you want 18s you might could start with 285/70/18 or something similar. Anyway, it will show you all of the specs for the tire size after you put the numbers in.

 

hello, blackmountain. I just saw this thread and I agree, you will want to go to a smaller rim size. The large diameter / short sidewall tires (20, 22, etc) have less compliance. You want tall sidewalls to cushion the rims from impacts and avoid pinching the sidewalls. Overall tire diameter may be a matter of how much tire will fit or it may be limited by gear ratios to something not too much bigger than stock but whatever the outside diameter, the smaller the rim diameter the better on rough ground.