Wheel sizes and offsets

[Boxhead]

Hi all,

Hoping you can help me a little, i have a heap of rims with tyres ( tyres are wrecked and need replacing) for my 1942 1 1/2 tonne truck. I need to work out what is right to put on the truck so i can get them blasted and painted. I have a couple of questions,

- what sizes should the rims be to suit the truck
- are the front rims usually narrower than rears?
- what offset should the front rims be
- do the rear duals have different offsets or are they the same but outside is put on
Reversed? And what offest should the rear rims be for the duals?

Any help would be appreciated to help me work this out so i get it right.

Cheers

Corey

[GB SISSON]

My '47, which is the same as your '42 has 8.25s on all six rims. All rims are the same width so they are all interchangeable. That's how they make dually trucks. More common is 7.50 tires and back in the original trucks they ran them narrower, like 6.00s and 6.50s. I just like big tires and I found a set of four traction tires in an 8.25 on CL for 50 bucks apiece. No brainer. Coker, Miller have most of the sizes with tubes and boots. Just depends , do you want heavy duty or original. They all fit, and we aren't hauling three tons of potatoes over the mountains in August anymore.

[Tinker]

Just a side note. Corky sold coker tire last month. Hope they continue making our specialty tires.

https://www.timesfreepress.com/news/...siness/483105/


Most likely business as usual. Figures crossed

[truckdog62563]

Before I do a deep dive into part numbers and cross references of Ford numbers to the manufacturer numbers, offset figures, and backset calculations, I would suggest you start by looking for Budd Company part numbers on your wheels. All 1942 trucks will have the same width wheels front and rear. Finding six that match will probably get you home free. The Budd numbers will probably be on the flat surfaces of the concave side center discs. You might also find numbers on the rear rim lips.

The below 1942 chart tells part of the story showing the wheels were either 6” or 7” wide. That cited measurement is based on the Wheel and Rim Association industry standard of the era. Today’s standard would redefine a 6” (measured lip to lip) as a 4.33” (measured across the inner rim base). Similarly a 7” then is today a 5.00”. Once you’ve found Budd numbers please come back and I can give you specs on them. Stu

[Boxhead]

Thanks for the replies guys,

I will check out the numbers and post back. Although yesterday i was looking and some have a different offset, i was measuring from the back lip of the rim to the back of the hub from memory some were 40mm difference..

I guess this may be due to different model wheels, i will check the numbers

Again appreciate the help

Cheers

Corey

[Cool 33]

Sponsored Links (Register now to hide all advertisements)

As years went by, the tire sizes and widths increased for heavier loads, the rim widths increased also to accommodate that tire width, since they should not rub together when mounted as duals. The narrower the earlier . But for many years they would interchange on the bolt pattern.

[truckdog62563]

That measurement you are taking is called “back spacing”, or “backset”. It’s a way to start, but it doesn’t tell you “offset” because it will vary depending rim width of each. The below charts let you do the math.

I also hope your wheels are all still assembled. Keeping rim and ring sets together as matching sets is important. Stu

[Boxhead]

Ok guys i got a few numbers but not all, i have another 5 to try and find the numbers on,

1. Sankey /56
2. Sankey /56
3. 2938
4. 41
5. Looks like C-84860 second line 3 48 (think its 48)
6. 9 47 81T-1015


Does this help at all? I will get to the other 5 rims as soon as i can and post the numbers.

Cheers guys

Corey

[Boxhead]

Thanks Stu and Cool33, very helpful

[truckdog62563]

Let’s go in reverse order.

6. An 81T 1015 with 9/47 build date gets us started. That is the Ford number for an industry grouping T623 wheel. It is a 20” x 4.33” (6” old system). Shown to have 4.5” of offset. I can connect that Ford number to two Budd Company wheels having different outer rims. Ford regrettably lumped such wheels under one part number. The first is Budd 35260 that has a Firestone “RH” style unbroken side ring. The second is Budd 34860 that has a Goodyear “LW” style split type side ring. Both 4.33” wide with 4.5” offset and 7.25” of backset. The rings DO NOT interchange.

The only wheels I’ve had with the Ford number stamped rather than the manufacturer number were produced for Ford of Canada. If I’m reading your dialect correctly I’m guessing you are an Aussie or from SA or NZ, which fits the Ford of Canada manufacture picture.

5. Your 84860 is I think a 34860 as above. Produced 3/48. You might look at it again. If you think it is clearly an “8” then I’ll have to dig into Motor Wheel Corporation references since that would be their numbering pattern.

4. 41 is nothing more that the year of manufacture probably. Kelsey Hayes wheels of the era were not numbered so this one will need to be evaluated based on width and backspacing to calculate offset. Make note too of it’s rim and ring design.

3. The 2938 needs a fifth digit. Rather than me guess what that might be please look at it again. If nothing else is there we’ll again have to go by rim width and backspacing to calculate offset. Note the ring type.

2 and 1. I have no reference for a Sankey wheel. But if these are AU/SA/NZ wheels there could have been some produced locally that I have no references for. Again we’ll have to do them like 4 and 3 above.

Let’s move on to your next batch. Stu

[truckdog62563]

While Boxhead gets me some more numbers, I’ll go over some tire sizing issues. Both of the 4.33” wide wheels covered above have 4.50” of “offset”. To mount them together in a DRW mounting would yield 9.0” of “DRW Spacing”. Every year the Tire and Rim Association publishes industry standards showing approved rim/tire combinations. Those 4.33” rims are approved for 6.50-20” tires. A set of 6.50-20s in a dual mounting require 8.30” of DRW spacing. If a guy was to mount a set of 7.00-20” tires it’d work because they require 9.00” of DRW Spacing. A 7.50-20” requires 9.70”, and an 8.25-20” requires 10.6”.

Every industry reference I have says an 8.25-20” needs a 6.50-7.00” wide rim (using the current standards). Except for the Green Bible. It lists a 5.00” (7” old) rim for that tire. I have come across some 5.00” wide wheels that have 5.50” of offset (11” DRW spacing) which give the needed DRW spacing. But I’d sure want to make sure of what I have before trying to mount 8.25s. Stu

[Boxhead]

Thanks Stu,

Appreciate it, your correct im from australia ( queensland actually). I wont get to the other rims until Monday as i will be working until then.

Cheers

Corey

[truckdog62563]

Okay, I’ll be here. Stu

[Boxhead]

Good morning guys,

Ok,

- the sankey wheels i can find no ther numbers
- the wheel with 41 on it has another number on the back C 42920 6 42 no idea why there is a 41 on the other side.
- the 8 is definately a 3 as you suggested stu
- there is no other number with the 2938, these numbers are a lot larger than other stampings. I may need to clean up the other side and see if there is anything.


Additional wheels,

- 4 x 81T-1015 (so same as above)
- BB-1015-D ( not sure)
- 60030 52 ( not sure)

Thanks for everyones help.

Cheers

Corey

[truckdog62563]

Okay, this is straight forward. You now have six 81T 1015s, so they give you a set. They are 4.33” wide (old 6”) and have 4.5” of offset. The Kelsey Hayes number is 21900.

The BB 1015D is an older wheel. 20” x 3.75” (old 5”) having the Firestone RH design rim/ring. It has 3 7/8” offset. Kelsey Hayes number is 19447.

The Budd 42920 is a 20” x 5” (current measurement system). It has the Firestone RH rim/ring and has 5” of offset.

The Budd 60030 is a 20” x 6” (current measurement system). It has the Goodyear LBW rim/ring design and has 5.50” of offset. Stu

[Boxhead]

Thanks Stu,

Appreciate the help, unfortunately looking at one of the 81T rims it seems to be pretty rusted.. so probably not useable. I will measure and look if i am able to use the sankey rims as outside duals maybe.

I will check the offset and rim width etc, can i run slightly different offset rims on the rear? I'm guessing so as long as the tires fit ok.

Cheers

Corey

[truckdog62563]

Depending on the width and backset of your two Sankeys you have several options. If the Sankeys are close in dimensions to the 81T 1015s you can mount them on the front and dual up four 81T 1015s that have 7.25” of backset on the rear. Their offsets yield 9.00” of DRW spacing which works with the 7.00-20” tires.

I think you might rule out use of the 60030 because of its 6” width and 9” of backset. The 42920 is 5” wide and has 8.25” of backset which might make it too much different than the others too.

The earlier BB 1015D is much narrower, and has only 6.25” of backset. You might be able to run it on a front corner teamed with an 81T 1015 on the other side, but I think you don’t want to try mounting a 7” tire on that narrow wheel. Plus, if it matters, I think you’ll see it has a different appearance than the 81T 1015. The hand holes are more of a triangle than those on the 81T 1015. In the attached FTE thread there are pictures of each that might help. Stu

https://www.ford-trucks.com/forums/1...6-1-5-ton.html

[Boxhead]

Thanks Stu,

I will work out a plan for the rims, none of these are the dreaded widowmakers are they? I will also try to have a look when i can get back to them.

Cheers

Corey

[truckdog62563]

None that I found record of are widow maker Firestone RH-5° style. Yours are mostly the Firestone RH type that has a solid unbroken side ring design. Tricky to service if you’ve not done it. I’ll post pictures below. I’ll have to go back up the page to refresh my recall on your Goodyears. I remember that the 60030 has the LBW split ring that is simple to service. The Sankeys I’d need to see pictures of to tell you what you have. Below are pictures. Please remember that the rim/ring sets should be kept together. The different designs, and even different widths within the same design, don’t interchange.





Here’s a picture of the RH showing the indents on the inner edge of the ring that allows it to squeeze over the lip of the base rim.



Here’s the widow maker RH-5°. Stu

[Boxhead]

Thanks Stu,

You have been a great help.

Cheers

Corey

[Boxhead]

Hey guys,

The info on the Sankey wheels, ( close to anyway)

225mm backset (8.58 inches)
152mm internal rim width ( wider than the 1015's) (5.98 inches)
114mm offset ( 4.5 inches)



Cheers

Corey

[truckdog62563]

Hmmm, those are singles. Too shallow to run as duals, but should work well on your front. I’d sure like to see a picture of them, or one of them. The below wheel is similar I bet, but is an 18” rather than 20”. I have two of these that were given to me by our FTE MH friend Chad (40fordmarmon6x6) who lives in the Toronto area. I’ve been trying to match these since then to make a set of four.

They have an outer rim design called the Firestone “R”. These have similar width, offset, and backset as your Sankeys. These are stamped with Ford CO1T 1015B and were made by Kelsey-Hayes of Canada under their number W23723. They have 4" offset, 8" backset, and 6" width. Could your Sankeys have this rim/ring design too? Stu

Edit - nope, those look to have a Goodyear type split ring. Stu

Edit #2 - thinking on this I fear you may have issues trying to run the same size tires on the Sankeys and 1015s. As I said above, the 4.5” offset / 9” DRW Spacing would work on the rear 1015s with a set of 7.00-20” tires, but that tire is really too narrow for the 6” wide front Sankey rims. I guess it could be made to work but you’d have the bead spred pretty far outward. Stu




Chad’s FTE thread.

https://www.ford-trucks.com/forums/1...ngton-6x6.html

[Boxhead]

Hi Stu,

They had a 7.5 tyre on them. Would you like more pictures?

[truckdog62563]

That would make sense, but a 7.50” set would be a risk on the rear. Rubbing of duals is dangerous. Mixing 7.50s on the front with 7.00” on the rear might work if you are okay with slightly taller tires on the front. Or, just accept that 7.00” on the front might be kinda narrow for the rims. Stu

Edit - I enlarged your picture and now see the second side rings that have fallen to the bottom of each Sankey base rim. I’m back to thinking those are the “R” type design. Do you see where there are/were rivets originally attaching the rings together?

So now I then have to ask too. Are you sure the Sankeys are 20”? Stu

[truckdog62563]

I’m interested in learning if your Sankeys really have Firestone “R” type outer rims. The only Rs I’ve had my hands on are the 18s I described earlier. This is a better picture of the unique double ring, and the riveted attachment of the rings together. There are numerous other designs having an inner side ring with separate outer locking ring, but this is the only design I know of where the rings were connected together.

I’d love to find a couple more of these 18” R wheels. They were commonly used on Canadian M-H 6x6s.



This is an original 1932 Firestone “R” advertisement. Stu

[Boxhead]

Sponsored Links (Register now to hide all advertisements)

Hey Stu,

Sorry i didn't see your last message until just now, i did not see anywhere rivets used to be on the rings to hold them together. They are definately 20 inch rims.

[truckdog62563]

Okay, I’ll have to see if there is another similar rim design that I’m not thinking of.

As you go forward with buying and mounting tires be safety conscious. Inspect the wheels for rust damage (blast or wire wheel), and when mounting tires use a cage when inflating them. There are many online videos of the dangers and showing what happens when a wheel fails. Stu

[Boxhead]

Thanks Stu,

The rims are all being blasted at the moment primed and painted. I would paint myself but they are doing it as part of the job. The rims look in pretty good shape, the 2 sankeys seem the worst but i wire buffed them a bit and came up ok. As for inflating in a cage, was this due to rim failure or the side rings failing? Or just general failure due to corrosion? I assume once blasted and integrity proven then painted it would be reasonably safe? Even so my local tyre shop will fit for me.

A question for you, where is the best place to buy brake parts for my model truck? E.g slave cylinders, brake shoes etc

Cheers

Corey

[truckdog62563]

A cage helps ensure that unforeseen micro fractures or rust damage doesn’t allow violent separation of the side rings. Once these wheels are safely together they tend to stay together. Glad you’re having them done professionally.

Brake shoes will probably have to be relined and, as I’ve read here and on FTE, new drums are NLA. Brake master and wheel cylinders in the USA are available from places like Chuck’s Trucks and others. Rebuilding locally is probably also an option. Below is Chuck’s web site. Stu

http://www.chuckstrucksllc.com/startframe.htm

[Boxhead]

Hi guys,

Ever heard of a rim with BB 1C15 - E stamped on it, i am assuming the C is a 0?
I am trying to see if these are compatable with my 1015's ( i need a couple more as a
couple of mine a damaged).

Chèers

Corey

[truckdog62563]

A BB 1015-E is a Budd 34909. It has the 4.33” wide Firestone RH rim and has 4.25” of offset. It is very similar to your 81T 1015s (4.5” offset) and should work in a DRW install if you don’t over do it on tire size. Stu

[Bob C]

Looked in the Ford parts book and BB-1015-E 20"x6" 1933-37 full floating
rear axle. I think 1933 should be late 1934 when the full floating rear axle came out.


Bob

[truckdog62563]

Yes, I agree that 1934 is generally thought to be the year Ford changed from the 5 x 6 7/8” pattern to the 5 x 8” pattern with the full floating axle.

And if you focus on my posting #4 above I explain that Ford was late to catch on to the change made to the industry measurement standards. During the 1930s the NWRA began posting both old and new measurements in their publications. Such as 5” (3.75”), 6” (4.33”), 7” (5.00”), etc. The Green Bibles through to the last 11/50 reprint edition have it wrong. Stu

[Boxhead]

Thanks guys,

Appreciate the information, i will message the guy and let him know they
May work for me.

Cheers

Corey