Matching tire width to rim width; some guidance

[Safety Guy]

Yesterday I googled this subject. I had always been a bit leery of the thought of mounting the 195/45-14s on 5.5" wide Miata "Daisy" rims, and mounting the 175/50-13s on 4.5" Aspire rims. This guy agrees with me:

http://www.carbibles.com/tyre_bible_pg4.html

From his article:

"The ratio between the section width and the rim width is pretty important. If the rim width is too narrow, you pinch the tyre in and cause it to balloon more in cross-section. If the rim width is too wide, you run the risk of the tyre ripping away at high speed."

He provides the mathematical formula to figure this and also a calculator he made up so you can simply punch in the numbers.

And his calculator says that minimum wheel width should be 6.5" with the 195/45s and 5" with the 175/50s. I was planning on running the 195/45-14s on stock Miata 6" wide rims, and I have to say that seems safe enough, but it confirms my hesitation to do so on the Daisies.

Here is Yokohama's tire width chart page:

http://www.yokohamatire.com/tires_101/customizing/rim_wheel_width/

It only shows some of our tire and rim choices, but it seems to agree with the previous site.

So far I've not heard of anyone having any problems with the tire/rim matches I was cautious about, so maybe some folks overstate it. But I'd feel a lot better NOT running too wide a tire on a skinny rim. As you get into the lower profile, higher performance tires, be more careful.

A 175/70 on an Aspire rim (4.5") should be fine, but if you're running the ultra low profile 175/50s, just be aware.

Thoughts?

Any other sources of tire/rim width matching guides?

Remember, it's at the limit that any dangers would make themselves known.

Karl

[blkfordsedan]

Sounds like you're on track. You can divide the cross section (i.e. 175 & 195) by 25.4 to get the width in inches. Then compare to your rim width. Like you said, the taller the aspect ratio (i.e. 70, 50, 45, etc.) the more forgiving the sidewalls and the wider the variance in acceptable rim widths. My F250 has LT245/75's on factory 7" rims and it fits perfect. However, my Mustang has P245/45ZR's on 8" rims, and I doubt you could even mount them on 7" rims.

[htchbck]

I've put over 100k on 185/60R14s on ELX 7 spokes (14x5) without a problem. And those saw some "highway speeds" back in the day when I had a BP in the silver car. Redline was at 85MPH in 3rd gear :!:

[JPT]

The old school rule of thumb says for best handling use a rim width of 75% to 85% of tire section with.

This rule is old though (back when radial tires first appeared).

Some auto manufacturers like putting wide tires on some relatively skinny rims. Ford put 215/60s on a 6" wide rim (70.5%) and 175/65 on a 5" rim (72.5%).

[71Montego]

BFG used to have a catalog that listed the recommend rim size for all their tires but it worked for any tire. I used this when I worked at the auto store.

[sketchman]

I personally know of 205s on 6" alloys that never caused an issue till they balded beyond use, and the owner was still running them till they started cracking open.

YMMV

[Bert]

Curious but my old heavy-half truck has original 6 inch wide rims and the door plate specifies 235/75-15 tires. Ordinary versions of these F150s had 5 1/2 inch wide rims and 215-225 tires.
I think if you take a good look at Aspire rims they are 5 inch wide.