31x10.50 on 15x7 rims..... | Ford Explorer Forums - Serious Explorations

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31x10.50 on 15x7 rims.....

Hello all. I have been reading the posts on larger tires on stock wheels. I think I would like to go with 31x10.5 on my explorer. I saw a couple posts where it was stated they would work on the stock 15x7 rims but 15x8 would be better.

Why is this and what are possible problems that might arise from using 15x7 instead of 15x8.



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A 15x8 would support the tire better, would give it a wider stand. Besides that it looks better, it gives it a little bit more stability when cornering. Theoreticly, driving VERY fast through a curve with the tire pressure too low, it's more likely it the tire gets off the narrow rim than off a wider one. But 31X10.5 are anyhow not the ideal dimensions for driving fast through corners, and I really don't think you risk anything using your 15x7.

BTW, this is donkey boy's 100 post, I also have two Exporers to my name :D :D :D

[Edited by donkey boy on 07-17-2000 at 12:24 PM]

Just as a general rule of thumb,...you want to go as wide as your going tall. This will keep the vehicle as close to being stable as possible. A 15x8 rim will spread the width of the tire out over a greater distance as give you more tire to the road(stance, traction,...). If off-roading,..A wider tire on narrow rims will tend to pop their bead easier than on wider rims and offer more tread to the terrain(traction).
All that in mind, you can run your 31x10.5's and not have any problem, but it would be better if you put them on 15x8's. If the expensive rims are out of your budget, search for used or find some cheap chrome nuggets until you have enough to get the ones you want. If you want more input, select the search option and read other info to help you in your quest.
Good luck!

I wouldn't worry much about going with 15x8s. You might be a little bit more stable in the turns and your overall diameter will be a hair taller, but it is not that significant.

I had a set of 31s on my ranger for 45k miles at about 30psi, with even wear and good handling.

Contrary to what Goober said, I have heard that you are more likely to pop the beed on a 15x8 vs. a 15x7. I have heard specifically, from RangerX that he never poped a beed with 33x12.50s on his 15x7s, and it wasn't until he went with 15x8s that he first poped a beed.

just my 2 cents.


31x10.5's work FINE on 15x7's

My wife's 98 Explorer has 31x10.5 BFG AT KO's on the stock aluminum 15x7 rims. They fit FINE. She goes around corners like crazy, absolutely no issues.

The supposed danger of pulling the tire off the rim is from airing the tire down (e.g. 5 psi). If you're doing that, you should be equipped to pop the tire back on (and you'd likely be running 33's or 35's or bigger on 15x10 rims).

I have 31x10.5's on my Ranger with 15x8 AR 757's. When I suddenly have money buring a hole in my pocket, I'll get a Duff lift and 33x12.5's, and I'll keep my 15x8 rims. Heck, I know a Ranger guy running 35's on 15x8's, and another one running 31's on 15x6 steel rims.

Don't sweat it, new tires are one of the best improvements you can make to your Explorer.


Hi Jonathon,
There is an advanage to running 31's on 15X7 rims, It balloons the tire out more around the rim and helps keep the outside of the rim safe. It also makes it harder to pop the bead on the tire. Goober is incorrect on what he said in his above post. I run 31X10.5's on the stock rims and DON'T have any problems, either on road or off road. Take a look at any hardcore rig and you will see that most if not all of them run a slightly smaller rim than what the tire manufactures call for, you will notice how they balloon out away from the the rim and are not anywhere near being straight even with the edge of the rim. Get the point? ;)


Thanks for all the replies. I will probably be replacing the tires in a couple weeks. Trying to find out now if my dealer can adjust my speedo while I wait and do it for me cheap.

Next step after this is the Trailmaster lift!!

I'll try to get some pics up also.

Thanks again


OK, OK,...so perhaps I am incorrect about some of that. I never said I was an expert :p . Having never been through the trials and tribulations of Truckhaven, Moab, rockcrawling, ...etc.. I cannot accurately say what will happen. I only convey what I have been told and draw upon my limited experiences in the softer earth(a.k.a mud/trails..). I didn't mean to say that it couldn't be done or that it shouldn't be done, rather from a safety standpoint( and, again from what I've been told), it seems to be safer to run a wider tire on a wider rim.

Ray, I understand your point about the tire ballooning out to keep it away from the rim and this was why I got the KO's, they have an extra lip around the rim to give it a little more protection. Just one question though, does pushing the tire out like that make it more suceptable to cuts? or (in your experience/opinion not really make much of a difference?)

The bead popping thing,...it has never happened to me so perhaps I'm not inclined to comment on that subject.

Just my opinion, but I think safety needs to play into tire/rim choices. Some of you fellows who use their trucks to the extreme can certainly see that ( shake your heads up and down ). All I was trying to say was that.

For those who run the larger tire/original rims, what size tire would start to be unsafe, for 15x7, 15x8,....?

As always, I retain the right to modify my comment to make me look as good as possible( god-like if you will ). :D Now bow before me... :)

Safe sizes

Jeff (i.e. Goober),

I run 33x12.50s on my stock 15x7s. The minimum manufacturer recommended rim is a 15x8. This size works fine if you drive in a mild manner!! I repeat, No High Speed Cornering!! In order to get the treadlife I am looking for I have to run about 20psi, so the tires roll quite a bit in the corners. If I had closer to 30psi only the center of the tread would touch the ground, and the tires would wear very fast.

If I had the money I would have definately gone with 15x8s, but my student budget wouldn't allow that.

With 15x8s I think you could run much higher air pressures and handling would be improved quite a bit. But a 33 isn't ever going to be your speed demon tire choice.


Ray, I understand your point about the tire ballooning out to keep it away from the rim and this was why I got the KO's, they have an extra lip around the rim to give it a little more protection. Just one question though, does pushing the tire out like that make it more suceptable to cuts? or (in your experience/opinion not really make much of a difference?)

Only if you are rock crawling, but then you are aired down and the side will buldge anyway. You can fix a tire if it isn't too bad, but it's darn hard to fix the wheel once it's bent. Just ask Rick.
The one thing I like about the KO's is that it has 3ply sidewalls. I have a slight tear on the sidewall portion of a new KO, but not deep enough to make it loose air. It wasn't as bad as Rob (GoFast), he had to put quite a few plugs in his to keep the air in. Still had a slight leak.

Could I get some good comparison pictures of 15x7 vs 15x8 with 31x10.5?

...Click on "The Squirrel" in my signature...31'x10,50 and 32x11.50 on stock deerhoof 15x7 wheels..;)

Congradulations on bringing a Thread out of Death. 9 Years must be some kind of record