Questions: Narrow Wheels w/ Large Tires (1 Viewer)

[Will Van]

Hey guys, I have a few questions about narrow wheels with wide tires. I often see relatively narrow wheels with tires mounted on them that are outside the recommended rim width for the tire.

A great example of this is people who run OEM FJ40 steel wheels with 33"x10.5"x15" BFGoodrich tires. The FJ40 wheels are 15"x5.5". The recommended rim width for 33"x10.5"x15" BFG tires is between 7" and 9". Significantly larger than the 5.5" steel FJ40 wheel width.
@wheelin62

fj40 wheels on fj60. Need Pics!!!



Here is another example. @Shebamacalla runs 315/75/16 BFG Mud Terrains on 16"x7" Tacoma steelies with 1" spacers. The recommended rim width for that size tire is 8" to 10".

Jason's FJ6.0 Vortec Overland Build


My question is, is there any drawback to running a smaller rim width than is recommended for the tire? Is it unsafe? Will national tire centers like Discount Tire or Costco mount tires on wheels that are smaller than the recommended range? It's so common that it doesn't seem like a big deal, but I just didn't know.

Here are the specs for rim width per the Tire Rack website: https://www.tirerack.com/tires/tires.jsp?tireMake=BFGoodrich&tireModel=Mud-Terrain+T/A+KM2

 

[SteveH]

Some Discount Tire stores are ouchy about mounting 'too wide' a tire on a narrow rim. Also, tire lift can be shorter due to the narrow rim not supporting the tire as well as a wider one would. I had one Discount tell me they would not mount a 31x10.5x15 on a stock FJ60 rim (6" wide). I went to another store, and they didn't say a word. I would not sweat this one at all, unless you're going way stupid and putting a 33x12.5 on a stock rim or some crazy thing like that.

 

[mattressking]

Tires are a touchy subject for people. Once the bead is set and properly filled with air, you'd be amazed how much a tire can handle. Tire manufacturers/dealers/shops that don't mount/sell the recommended sizes for your stockers are avoiding any mere possibility of lawsuits caused by installing outside the manufacturers recommendation.

Just for giggles I want to try and see how beading a 12.5 to a 6" wheel would be. The last couple dozen sets I've mounted were grossly undersized, things like a 215/35 on a 10" wide wheel. No issues, just keep air in it like any tire and you will be fine.

Even aired down to 18psi on stock wheels it has never debeaded while crawling for me.

 

[Tancruiser]

10 .5 on a stock rim doesn't seem to be issue on any of my cruisers over the years 12.5 then you have a problem.

 

[gregnash]

10 .5 on a stock rim doesn't seem to be issue on any of my cruisers over the years 12.5 then you have a problem.

This seems to be a more recent thing and also seems to very greatly by region. Had my discount tire not give me any issues, but when I called Costco, Les Schwab and Tires Plus locally they all told me negative as it was not within the "proper specs" for mounting the tire based on the mfg. ratings.

 

[mattressking]

This seems to be a more recent thing and also seems to very greatly by region. Had my discount tire not give me any issues, but when I called Costco, Les Schwab and Tires Plus locally they all told me negative as it was not within the "proper specs" for mounting the tire based on the mfg. ratings.

Tire irons and soap are your friend

 

[Will Van]

Other than perhaps getting some pushback from national chain tire sellers/installers, is there any downside to installing the tires on a narrower wheel? Does it affect performance? Wear pattern? Longevity? Safety?

 

[Seth S]

Wide tires on a narrow wheel can affect wear, handling, and performance depending on what you are doing. If the tire is too wide it wont support the rim properly and could lead to some very odd handling and premature wear. Here is a picture depicting one scenario applicable to a motorcycle/bicycle:

Essentially the risk is that when the tire gets too wide the side walls don't align properly with the rim and the rim sort of floats in-between the sidewall vs inline with the side wall....if that makes sense...so when cornering/braking/accelerating the tire can deform more than it should and can cause adverse handling effects to manifest. However a few sizes wider than stock should be fine.

 

[Will Van]

Wide tires on a narrow wheel can affect wear, handling, and performance depending on what you are doing. If the tire is too wide it wont support the rim properly and could lead to some very odd handling and premature wear. Essentially the risk is that when the tire gets too wide the side walls don't align properly with the rim and the rim sort of floats in-between the sidewall vs inline with the side wall....if that makes sense...so when cornering/braking/accelerating the tire can deform more than it should and can cause adverse handling effects to manifest. However a few sizes wider than stock should be fine.

Awesome. Thank you for the help! It seems 33"x10.5"x15" BFG All-Terrains/Mud-Terrains on FJ40 wheels (15" x 5.5") is really common without any incident. I think as long as I stay within that range, I'll be alright.

My ideal setup is a set of 315/75/16 BFG Mud Terrains on a set of 16"x7" Wheel Vintiques "Smoothie" wheels. At that point, I'm only 1" different than the recommended wheel width (8" minimum recommended wheel width per BFG; 7" wide wheel), versus 1.5" on the more common 33" BFG (7" minimum recommended wheel width)/FJ40 steelies (5.5" wide wheel) combo.

I think @Shebamacalla's setup is badass!

I want to duplicate it with some Wheel Vintiques, but I want to make sure it's safe.
...maybe I should just ask Shebamacalla