Widest tire on stock rim?

[alkaline747trio]

Wanting to use the stock rims to save a little money, so I am wondering, what is the widest tire that you would reccomend to put on a DD? Just want the actual inches, not any tire suggestions.

Thanks in advance,
Logan

 

[cruiserdan]

Any wider than 315mm will "pinch" the sidewalls in and make the tread "crown". You can run them but you are riding on the center of the tread only.

 

[alkaline747trio]

If I went wider than that, would underinflating them slightly solve the problem, or just be worse on wear.

 

[cruiserdan]

Under-inflated tires run hot and come apart. Ask the Ford Motor Company and Firestone Tire about that one.

 

[stuck in GA]

Just curious ... why do you want such a wide tire? Looks, performance, both?

 

[alkaline747trio]

Both, I think a wide tire looks nice, and I do a lot of sand driving, takes too much time to deflate/re-inflate to keep myself out of the soft NC OBX sand. Also, what does 315mm convert to in inches? 12.50, 13?

 

[cruiserdan]

315 / 25.4 = 12.401575 inches.

 

[alkaline747trio]

Guessing there are 25.4mm in an inch, thanks...I still don't understand metric tire sizes, it's not just height x width, it's a damned equation. Can anyone help me out on that real quick, cause I know what I'm talkin about in SAE units, but metric tire sizes screw me up bad.

 

[cruiserdan]

Um,

Because 25.4 mm = 1 inch.

 

[alkaline747trio]

Yea, I edited my post...re-read and re-help..lol

 

[cruiserdan]

Guessing there are 25.4mm in an inch, thanks...I still don't understand metric tire sizes, it's not just height x width, it's a damned equation. Can anyone help me out on that real quick, cause I know what I'm talkin about in SAE units, but metric tire sizes screw me up bad.

Let's think about it like this:

It's all about aspect ratios. A 70 series tire has a sidewall height that is 70% as high as the tire is wide.

Example: 305/70/16. This tire is 305 mm thru the section which means that the sidewall is 213.5 mm tall (70% of 305 mm). So, 213.5 mm for each sidewall = 427mm, or 16.81 inches. The wheel diameter is 16 inches, therefore the tire is 32.81 inches tall(16 + 16.81 inches) and 12 inches wide (305 / 25.4 = 12.0078).

Bottom line, a 305/70/16 is roughly a 33-12.00-16.

Better or worse?

 

[alkaline747trio]

It puts things into a better perspective for me, thanks for the explination of that horrid forumla you have to do to figure out the size of a damned tire. 12" is the widest I should go, eh? Thanks alot.

 

[cruiserdan]

You could sneak a 12.50 on there too. A lot of folks run a 315/75/16 which is just a tad under a 35-12.50-16

 

[wb1948]

I have read some threads on pirate where people were successful running 14.5 on 8 inch wide rims. I am not sure what their use was or any of that, but some people have had success. I am not suggesting you do this.

 

[Bear80]

for what's it is worth, I run a full 12.50 on a 7" wheel. I have also run a understated 12.50 bias ply. The bias ply makes the "crowning" very noticalbe. You won't be able to tell the "crowning" on the radial, it wears normal. As for the bias ply it was very very noticeable, plus it was more like a 13-13.50. Anyway lower psi helps and well made tires can handle the lower psi and heat. I drove the bias plys at about 30 psi for a 2,000 mile round trip and they lasted for years afterwards and I ran them well under 20 psi on the street. The radials I run just under 30 psi for the street, mid 30's for trips.

 

[Silicon 70]

Does this formula also apply to FJ80s with a stock rim size of 15x7? Someone on this site sold me some 15x8 rims, so I'm debating which size tires to put on it as well.

 

[ryanjl]

For 15" rims you don't need to worry about metric sizes as all the tires available are measured in inches.

 

[Riad]

Putting a 12.50" wide tire on 15X7 wheel is pushing the limit. 15X8 is seemingly right for that wide of a tire. My opinion, I would go 15X10 for any tire that is 12.50" wide. With 15X8 I would do upto 11.50" or 10.50".

 

[wb1948]

With 15X8 I would do upto 11.50" or 10.50".

Based on what?

 

[cruiserdan]

Based on tire manufacturers' recommended rim widths. Most 12.50 width tires have a recommended width range of 8.5 to 11 inches. Of those recommended widths 10 inches is the ony "common" width.