Axle width/tire question

[jelfert]

I have a 1958 fleetside that I want to mount some MT sportsman radial 29X18.00R 15 tires on the rear. I have the stock frame width. I'm sure a few of you on here have mouonted these tires on your trucks. What axle width, brakes and wheel backspace did you use? I will be using willwood disc brake conversion. The plan is to have the axle built (4 link) with the brakes installed and shipped to me so I want to get it right the first time!

[mr48chev]

You have to be kidding yourself if you believe you can get those tires inside the fenders of the truck with a stock axle and stock frame.

This is a photo of the tires my buddy has for his 48 truck that are the same size as you are asking about He had to narrow the rear axle several inches and then build a custom narrowed rear portion of the frame to clear.

[jelfert]

Where did I say I was using the stock axle???? That truck doesnt have the same frame as a 58..... I will be buidling a frame as well. I'm looking for some factual information...i know things have to be narrowed. i'm wanting to here from people who have done and know how much and if there are any reccomendations. thx

[mr48chev]

Ok, I see that you did ask what axle width. Sorry about that, all I saw was the clear the clear the stock frame with big tires Written by a guy who has it in his first post on the board.

My buddy likes super deep wheels and super wide tires so his rear axle is pretty narrow. The outside width from the outside of one tire to the outside of the other tire is probably pretty close to the same as you need though. It's too late to call him tonight but I can ask him tomorrow.

[jelfert]

Thanks. I'm pretty sure I've seen a 58/59 run 18s with the stock frame width. I'd like to keep the frame as wide as possible to have more room for the 4-link and exhaust. This 55 chevy has a widened rear frame to 40 inches....and those tires are 15 inch (I think). Its 6 inches wider than stock 55-59 frame.

[dwcsr]

Originally Posted by jelfert

Where did I say I was using the stock axle???? I will be building a frame as well. Probably going to be about 4 inches narrower. I'm looking for some factual information...i know things have to be narrowed. i'm wanting to here from people who have done and know how much and if there are any recommendations. thx

You can get a tire with a 18" section in there inside the fenders with 1" on either side of the tire without modifying the frame or fender.

Fender to fender is 76"
minus 2" each side for clearance
frame is 34"
So 76-38/2 = 19 inch wide tire section
You can make your axle what ever you want, I think i did mine at 54" and made it up with the wheels.
if you have the wheels measure the inside fender to inside fender (75) minus one inch to each side (73) and add the offset of the wheel, lay the mounted wheel face down and measure from the floor to the mount flange, lets say its 8" x 2 =16". So 73-16 = 57" axle flange to flange with the drum or disc on


Give some thought to the suspension and how your hanging it, In rail or out of rail. I did mine Tri bar air ride in rail with a pinion center axle. I don't think I'd do a pinion centered again unless i was racing it caused to many fab issues. Narrowing the rails gives you less real estate for hanging suspension in side the rails and less stability on a daily driver. But narrowing the rails does help if your going outside the rails with something like a 4 bar.

[mr48chev]

A 34 inch frame width as Dave mentioned above should work. I was thinking they were closer to 40.

[dwcsr]

Originally Posted by mr48chev

A 34 inch frame width as Dave mentioned above should work. I was thinking they were closer to 40.

AD's are 42. TF's are 34.

[jelfert]

Thanks guys this is very helpful! I'm going to run all the componets inside the frame. Probably a triangulated 4 bar. Keeping the frame stock width will simplify things.

[dwcsr]

Originally Posted by jelfert

Thanks guys this is very helpful! I'm going to run all the componets inside the frame. Probably a triangulated 4 bar. Keeping the frame stock width will simplify things.

If that's your plan I would suggest you do a centered pumpkin and not a centered pinion it will give you equal room on each side to weld on the tabs.

[jelfert]

Yeah a tri 4 bar may not be the way to go with a 34 inch frame width. Its pretty tight in the above picture with a 40 inch frame. Probably wont have proper angles on the upper bars as it is 6 inches narrower.

[Speedbumpauto]

Mine's 38 flange to flange. Stock width rails and an offset pinion/centered housing. I'm running Hoosiers 31x16.50x17 on Weld 17x13.5 with 3.5 backspace. So I'm one size smaller tire than you want. With that set-up I have 2" from tire to frame and 2" from tire to fender. Used a Morrison 4 link w/panhard bar on a 9" Ford. I just got it on the road so I can tell you that part of it works. Since you're having someone else do the housing, I'd probably go a little longer on the housing because you can always make that up with backspace. 3 1/2" is the shortest backspace I've seen on these wheels so if you make a mis-calculation on the short side, you're done.

[jelfert]

Nice 55! What kind of brakes are you running and how much does it add from axle flange to wheel mount surface?

[mr48chev]

Good info there Speedbumpauto.

I was thinking about how far apart the spring pads on the stock 55 rear axle I have out here are but the stock springs sit outside of the rails on them rather than under the rails.

[dwcsr]

Originally Posted by Speedbumpauto

Mine's 38 flange to flange. Stock width rails and an offset pinion/centered housing. I'm running Hoosiers 31x16.50x17 on Weld 17x13.5 with 3.5 backspace. So I'm one size smaller tire than you want. With that set-up I have 2" from tire to frame and 2" from tire to fender. Used a Morrison 4 link w/panhard bar on a 9" Ford. I just got it on the road so I can tell you that part of it works. Since you're having someone else do the housing, I'd probably go a little longer on the housing because you can always make that up with backspace. 3 1/2" is the shortest backspace I've seen on these wheels so if you make a mis-calculation on the short side, you're done.

Are you sure its 38 flange to flange. The rails are 34 and I see at least 4" on each side just to the backing plates

[dwcsr]

here is the one I did on mine about 10 years ago. Narrowed to 54 , Torino ends and explorer disc brakes

[jelfert]

Dave,

Thanksfor the pics. What kind of wheel/tire combo is that? waht backspace do you wheels have? Looks good! I can see how the centered pumpkin is the way to go.

[dwcsr]

Tires were g-Force T/A Drag, P 325 /50R15. I don't remember the backspace/wheel center line but they are American Racing 200S 15" x10 5x5

[jelfert]

Originally Posted by dwcsr

Are you sure its 38 flange to flange. The rails are 34 and I see at least 4" on each side just to the backing plates

Maybe 48 inches? I dont see how it could be 38"?

[Speedbumpauto]

Sorry guys, I mis-spoke. I should have said inside backing plate to backing plate, which is the only easy place to measure now that it's together but had it up in the air yesterday.(brain fade) That, or close to it, was the measurement I used when I narrowed the tubes on the rear. I don't have my notes on the actual flange to flange measurement. Ordered the axles from Mosier with the std. 9" bearing spacing which is very close to 3 1/2 since the edge of the rim inside is almost even with the backing plate. The HD Ford drums on the rear add 1/4" to each side. Apologize again, didn't mean to be leading you astray.

[dwcsr]

Generally if you measure from the backing plate you will need to add 1/4 for the plate and and 2 or 2-1/2 for the brakes depending on what you use plus the drum or disc thickness. So 3, 3-1/2 is in that range. Your probably at 45" flange to flange, My is further away from the rail than yours and I'm at 52 or 54"

[jelfert]

I laid mine out on graph paper and figured I need 51 inches from wheel mount surface to wheel mount surface. Section width of the tire is 17.6 so this gives me atleast one inch gap between the fender and also the frame. Backspace of the wheel is 5.5 in and the wheel 14 in wide. I'm gonna buy a complete axle so I can give them the 51 inches as the total length with the brake and rotor installed.

[Speedbumpauto]

When you subtract the differences in back space, that put you very close to what I have. I think you're smart with more backspace because you can "tune" most wheels in 1/2" or increments down to the 3 1/2 minimum. Gives you a little breathing room. Sometimes I get a little carried away with the deep dish look.

[jelfert]

Yeah I will probably go 50.5 inch total width. That will put me a little closer to the frame but I can shim it out if need be. I want to stay as far from the fender as I can. 1/4 inch can make a difference.