OT (kind of) - dually tires

OK, fellas (and gals), I am planning to run duals on my 47 Dodge and want ot keep them under the stock fenders. My question is: if the current tires are 7.5 x 16's, what is the shortest tire that will fit the 16x8 rims and not rub when assembled as a dually?

Edit: I'd possibly like to run wide whites, too if available.

 

How will you keep the tires under the fenders without tubbing the rear section of the frame and building wheelwells in the box? What rear axle are you using?

 

I'm planning to do just as you mentioned. I'm going to be narrowing a Dana 70 that I was given.

 

Ahh, I wondered. I'm using a narrow Dana 70 under my Diamond T, and there's NO way without tubbing it that it'd keep duals under the fenders. I had to pay for mine, dammit! Can't really say for sure about the tires, but a buddy of mine is running 235/75R 17's on the back of his Ford dually, with no sidewall scrubbing. You know you can cheap out on whitewalls by shaving white lettered truck tires. You want to run radials, don't you?

 

I would get the most common size that fits well, and make the fenders clear them. You don't want to pick an odd size and regret it later. We have a few trucks here at work with odd sizes, sucks having to order them, wait, and pay the premium.

 

Any other thoughts?

 

get a dually rear out of a motorhome, they are narrower than a truck rear. As far as tires go I would consider a 225/70 16 or a 235/70 16 if you want a little wider.

 

tow truck duelly rears are narrow

 

235/85/16 is the most common size 16 inch dually tire.

 

That's what mine is out of. 1972 Dana 70 and, if I measured right, it is about 10" wider than my fenders.

Is 225/70 the shortest that'll work?

 

It's all hard to say until you have everything mounted and situated - if I understand what you're doing correctly.

Without the trial and error, or the actual measurements of the fender clearances, it's hard to know for sure what'll fit where and why.

 

If you are not going to run 8+ ply truck tires there are lots of options. Here is a helpful link. http://www.discounttire.com/dtcs/infoTireMath.dos

It's hard to say exactly how wide you can go without the tires touching each other because the 16" dually rims don't all have the same offset.

 

There are a ton of things to consider. Will the truck be lowered? if it is will will have to go with a shorter tire. The 225/ 70 was taking into consideration that the truck is not lowered. If you want to do any towing or hauling with it a 60 series tire would be the smallest I would personally run. Do you have any pictures of you truck so we can see how it is setup, or more details on what you plan to do with it?

 

I think you could run a 255, but I've never seen wider than a 245 on a dually rim. BTW, they are almost always 16x6, so a 235 is plenty wide as far as look.

 

I run 225/16's on my daily driver. I will try and get some pics if you'd like. Can't remember the width off hand...but I will look in the morning.

It lowered the gearing quite a bit, but the truck has a GV overdrive to make up for it. The tires, wheels and overdrive will eventually go into my '57 IH when it is closer to being done. (It has the narrower motorhome rear axle that the guys identified above)

The tires are Load range "E", so they are still good for haulin a trailer around.

 

I'm running 235 75 r16's on this truck

16.5" rims run a lower profile tire than 16's
16's are taller and narrower
You can run a 9.50-r16.5 tire on a dually. the shortest ones are 8.00-r16.5's
reading a tire...
a 8.50-16.5 is a bias ply tire on a 16.5" rim and had a sidewall width of 8.5" to get taller you also have to get wider.
an 8.50-r16.5 is the same tire in a radial casing.
a 235 75 r16 is on a 16" rim. It nominally measures 235mm from bead to bead around the tread. the 75 refers to the height being 75% of the width so a 235-60r16 is 25% shorter and wider than a 235-80r16
if you want to find a tire that is as narrow as a 235-80r16 but is short as a 60 series subtract 25% from the 235mm. You'd need a 176-60r16.
To find a tire that is as wide as a 235-60r16 but as tall as a 235-80r16 add 25% to the 235. You'd need a 294-80 r16 for it to be as wide as a 235-60r16.
Tip on percenting... If you figure the percent difference between one aspect of 2 things then every aspect of those things will differ by the same percentage as long as the aspects od each thing are connected similarly within that thing.
as an example:
You can but don't need to figure out complicated formulas for changing tire sizes and speedometer changes. you would drive as close to 60 miles/hour as you could guestimate, It's one mile per minute. use a stopwatch and hold steady for 10 minutes. the 10th's of a mile off calibration for 10 miles represent one percent variance of mph.
You can also use your odometer without the stopwatch just drive 10 miles. each 10th off is 1% mph off.
If your odometer is 10% off you can fix it with a tire that is 10% bigger in the same aspect ratio you already have. want 10% bigger for height go from 235-75r16 to a 265-75r16. you have to bump up your 10% (.10) to 25% (.125) to make the 75 into a 100. then multiply 235 by 1.125 to get 100% of 235 plus 1.125% of 235 which is 264.xxx.... or you can just figure the 10.25% and add it to the 235 separately.

That much bigger of a tire would be like a 10% overdrive, cool!
have fun

 

My truck is still in the "raw" right now (still stock - 47 Dodge 1 ton). I do plan to lower it substantially. My plans for now are to make it a street/strip truck, so the 1 ton/hauling duties won't neccessarily be an issue (well, maybe light duty use).

Basically, I'm just looking to see how short of a tire I can go with that'll not rub on the other dually tire.

 

Since you plan to narrow the axle anyway why not start with the tires you want to run and figure out how much to narrow the axle from there.

Have you considered having wider wheels with more offset made? I' sure it would be spendy, but might help get what you want.

 

A dulley rear is the widest of rears. Use a 350 dump truck rear. It is under the 8' with. School bus rear will work. But wou wont have the 4'
between the inside of your wheels.

 

I would go with a 225/60 16 personally I had a '99 Chevy crew cab and that is what I ran with a 7" drop. Never had any rubbing issues, even when I was towing and blew a helper bag.

You could go with a 50 series tire but I would not tow with it. A 215 wouldbe narrower but it would not look right in my opinion, too narrow.

I am actually going to be putting a '41 Chevy 1/5 ton cab and sheet metal on a 1 ton motor home frame. I do plan to lower it and will be running a 235/70 16 (most likely) in the front so it will have the appearance of the bigger 1.5 ton style wheel. I will be lowering the back o match with bags for when I have a load. It will be a flatbed truck.

 

Like I said, I already have the D70 out of a motor home, so I am not looking for a dually rear. Also, I have an idea as to the width of tires, I just need to find the shortest tire suitable for dually use. I plan to run the duals for everyday useage and a single wide tire for raceday.

Thanks. That's what I was asking for all along .

 

Just put car tires on it if you're not towing with it. They go down to rubber bands for econocars.

Griffin, I'm a little confused by this thread, because asking what's the shortest without rubbing is, well, kinda backward. No offense. Height is the second number on the tire and isn't directly linked to the width.

Or when you say rub assembled as a dually are you talking about rubbing on your fenders instead of rubbing the other tire??? But again, rubbing is so much more than height and makes me equally confused.

Only real advice I'll offer is you made a good decision to use 16s, in the last few years 16.5s have had a price climb and manfacturers are reducing available sizes. Quickly becoming a specialty tire.

Good luck

 

The section width is directly related to the height by the sidewall aspect ratio (70 series, 50 series, etc). Some tires have the same diameter, but different section widths (i.e. sidewall bulges). I was hoping someone might have enough experience with metric sizes to be able to advise me as to what metric tire will work on my rims (which currently have 7.5x16 tires) that'll be as short as possible and not rub and without having to deal with counter-jockys that only know what is on the computer screen.

I'm narrowing my axle, so fender rub is not a concern. When I say rub, I mean no contact in between tires.

 

+1 on the common size tires. Keeps the price down and availability up.

I can't see any way to put duals on that truck without tubs unless you widen the fenders and that would look like the pits.

 

Now we are getting somewhere. Yes, sizes are linked by aspect ratio, I somewhat misspoke and was trying to get at the fact you can get multiple aspect ratios for a given width.

So really the question is what's the smallest 16" load rated tire you can buy? Or do you have some kind of approximate diameter you're shooting for? Or does load rating matter, if not car tires go all the way down to 195/50-16. No dual wheel rub concerns and they're certainly the shortest

good luck

 

Diamondback sells a nice 215/85-16 radial, wide-white, or not. If you are running the "standard" Budd style 16x6 dually rim, these should be just fine, so long as you don't over-load it.

http://www.dbtires.com/2009_catalog/hi/24_SteelRadials3.htm

I think these would look really sweet!

I would match the inner and outer tire. Mismatching them can have strange and sometimes expensive results, ask me how I know.

On narrowing the Dana 70. Yukon Axle and Gear makes 35-spline, cut-to-fit axles, in 1541H steel, in three lengths (31-33.5, 34-36.5, and 37-39.5"). You may see them listed as Dana 60 axles. The Dana 60 35-spline axles are the same as the Dana 70 35-spline axles. If you end up needing shafts that fall into one of these three ranges, they can save you some serious green over a custom make axle. They cut with a cutoff wheel. I use them frequently on 4x4 stuff, including my own rig, and have had no complaints. They are typically about $100 each.

 

Hey, now those are sexxay!!! and exactly what I had in mind. Thanks for the tip on the axles. Right now, I don't know what length I'll need. Hopefully, I'll have more info in the next few weeks when I am able to actually start really working on it.

 

If you have any questions about narrowing the axle, just let me know. I narrow full-float Dana stuff as a regular part of my business, keeping them full float, in the process. I can give you all of the info if you want to ditch the (HEAVY!) drums and go to discs too.

Don't worry about the axle shaft length now. Take the rear hubs off of the axle and bolt both wheels to them, both sides. Get 'em where you want them. That will dictate the axle width, and thus the shaft length.

 

Thanks!! Yeah, I plan to do a disc conversion and I've found lots of info for it online. I'll definitely get in touch with you when I'm able to start getting my hands oily (although, I do hate the smell of gear lube ).

That's what I was planning to do to determine the axle width.

Thanks for all the help!!

Mike

 

225/75R16 pics as promised...





Probably too late, but my word is my word...