for those who want a tire shop to mount them, many will not put 33's on a 7" rim because manufacturers specify minimum rim widths. As an example, according to BFG 285/75/16s ATs call for a minimum 7.5" rim.
What's diff. between 285/75R16 and 33x12.5x16..
- Thread starter crappyone
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- #22
That's what I thought. I've seen a Chart that told but I can't find it again. I would mount if I knew how and had equipment. So if any of you know where the wheel/Tire size chart can be found be helpful. Thank you
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- #24
Actually was looking at the Destination M/T's. They have best reviews for Off Road Traction on tirerack.com. I also like the way they look. But the Sidewalls seems like they'd be stiff and wasn't sure if they'd bend/stretch/form or whatever to the 15x7's. And Thanks MoJ, I'll check out BFG site for chart, but is that only with BFG's? Thanks a bunch for all the help
It should be pretty much the same for any tire although I'm sure there's some variation out there. I've read before where the width of the rim should be approximately 70% of the tire but there's always acceptions to the rule as many of us here have experienced.
The Destination M/T at a 33x12.5R15 has approved rim widths of 8.5-11" according to their brochure. the 285/75r16 on the other hand has rim widths llisted of 7.5 - 9"
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- #27
Cool thanks. My rims are 15x7 though. So do the 8.5's work on 8" rims? Or do I need 9". So looks like I'd have to get new rims either way if I want to upsize. Well I guess I'll see what I can do. Thank you much for the help and info Cruiserheads.
crappyone said:
First, you need to do some research including asking questions here and becoming familiar with tyre and wheel measurements. Many of the tyre and wheel manufacturer's web sites have primers.
If you have a tyre that calls for a minimum wheel width of 8.5" then you need that size wheel or larger to meet their specs. As some have stated, you can run rims that are not designed for a specific tyre size but many/most tyre shops will refuse to mount the tyre due to liability concerns. Personally, I would not deviate very far from manufacturer recommendations on something like rim width. They have some pretty smart guys deciding what tyre works with a specific wheel width. If it's a trail-only truck then you may choose to deviate; if you are carrying your family on a long trip at 75mph then you shouldn't run your own experiments with tyre safety. Just MHO.
-B-
I take back my statement about the beads coming off with a narrower rim, however whoever said it was almost like running bead locks is living in "lala" land. I bet you that bead will not hold if the tire starts to “roll under” where a bead lock will.
However I still maintain that it is a bad idea and I quote (dunlop site)
"If the rim is too narrow, the flex point moves toward the shoulder area, creating heat buildup in the shoulder which reduces tire life and could result in failure."
"If carried to extreme, either too narrow or too wide of a rim, can result in uneven tread/pavement contact pressure causing uneven wear and potentially reduced traction, or increased vulnerability to bead dis-lodgement."
I have never seen a tire manufacturer recommend a 7" rim for a 12.5" tire... wonder why?
If you are using the vehicle strictly off-road a narrower rim will give you better side wall flex and since you aren't really relying on getting a lot of wear out of them or traveling at high speeds then that is fine. It’s toying with failure on the road though.
The general rule of thumb I have heard from everyone I know and that have built comp rock buggies is no more than 4.5" difference between the width of the tire and the width of the rim. Especially for vehicles primarily driven on the road, unless you are running something like 44x19.5 boggers where you can’t find a rim wide enough to meet that standard.
However I still maintain that it is a bad idea and I quote (dunlop site)
"If the rim is too narrow, the flex point moves toward the shoulder area, creating heat buildup in the shoulder which reduces tire life and could result in failure."
"If carried to extreme, either too narrow or too wide of a rim, can result in uneven tread/pavement contact pressure causing uneven wear and potentially reduced traction, or increased vulnerability to bead dis-lodgement."
I have never seen a tire manufacturer recommend a 7" rim for a 12.5" tire... wonder why?
If you are using the vehicle strictly off-road a narrower rim will give you better side wall flex and since you aren't really relying on getting a lot of wear out of them or traveling at high speeds then that is fine. It’s toying with failure on the road though.
The general rule of thumb I have heard from everyone I know and that have built comp rock buggies is no more than 4.5" difference between the width of the tire and the width of the rim. Especially for vehicles primarily driven on the road, unless you are running something like 44x19.5 boggers where you can’t find a rim wide enough to meet that standard.
- Thread starter
- #32
Well now that I have tire chosen. Would anyone know where to get cheap Firestone Destination M/T 31x10.50R15's. Cheapest I found them was $119, sorry just figured you guys might know of some good cheap place or something. Thanks again people you've been very helpful.
