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Technical Rims/tires for the 49 Chevy 3100

Discussion in 'Traditional Hot Rods' started by 49bruzer, Jan 24, 2019.

  1. 49bruzer
    Joined: Jan 15, 2019
    Posts: 4


    So I am on my first build of a pre 1960s vehicle and I am working on a 1949 Chevy 3100. I have changed my front suspension to modern day and its track width is 56". I am going to the junk yard today to pull a GMC Jimmy 10 bolt that measures 58". Online it looks like only a 70s Ford Maverick measures 56" for a rear end and those aren't piled out in the junk yard.

    I'm thinking I will have to add 1" spacers to the front rotors and then i am streamlined. I am hoping someone has done a similar build and can help me with what size rims/tires they went with. 16x6" smoothies, 4" backspace?
  2. Once you get the new rearend mounted, then you can measure and see what backspacing you need. A 15x8 is about the biggest wheel that will fit (with proper backspacing of course) in the rear, 15x7 is better for a little more clearance. A 255/70R15 tire will fit, with about 1/4 inch clearance on the 15x8 wheel if backspacing is correct. But a 235/75R15 on a 15x7 wheel will have better clearance. The main issue is the stock bed wall and the stock rear fenders just are not that much room between them. I think a rearend with around 60 inches wide at the wheel mounting surface is about right for the AD trucks.

    Your front I would wait and see what rear wheels you end up with and then get the fronts to make it look right with backspacing. If a spacer is needed, then you can figure it out.
  3. need a 60-61" rearend (wheel mount to wheel mount) then you can use a 15x7 or 15x8" rear wheel with a 3 & 3/4 " backspace such as a Chevy Rally wheel in a 7 or 8 " wide.
    you can run a 235 -75- 15" tire no problem,...if you use a rearend as narrow as a 56" you;ll have to add wheeltubs in the bed and run a real wide or offset rim.'s my Ad with a 15x8 rear rim 235 tire and 3 & 3/4" backspace rim.
    cokers 085.jpg
    mcsfabrication, Hnstray and mrhp like this.
  4. ...sounds like S-10 front,..they are too narrow, you'll need spacers or real deep offset rims (which don't look rite),..front wheel to wheel distance should be about 59-60"
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  5. Hnstray
    Joined: Aug 23, 2009
    Posts: 10,257

    from Quincy, IL

    Yeah, the S-10 waaay too narrow. Not only do they not look right, but the common 'fix' of wheel spacers or wheels with minimum backspacing is only a cosmetic fix at best. It a terrible way to compensate for the too narrow front end and destroys front end geometry......too much scrub radius, increases stress and strain on ball joints and wheel bearings, increases the tires wandering with every road irregularity....nothing good comes from it.

    Your are correct about the rear axle width range .........the originals are about 62" but that was with narrow rims. A slightly narrower axle, as you suggest, provides room for wider wheel/tire combo.
  6. Mr48chev
    Joined: Dec 28, 2007
    Posts: 24,590


    As Rusty1 said, you need a minimum of 60 and 61 is better wheel mount surface to wheel mount surface. Backing plate to backing plate doesn't mean squat when figuring out how they will fit the truck.
    I've got a 74 Nova rear under my 48 and cannot run a stock Chevy car steel wheel with what you would consider a standard offset on the back. Had one as a spare and ended up having to pull a front wheel off an put it on the back and put the spare on the front to get to a tire store and give them a good laugh. Since then I carried an old Chrome reverse wheel as a spare that had enough offset to work on the back.
    Not sure if you have an S-10 stub or stock MII on the front as both are on the narrow side under and AD. About the only coil spring front you can put under an AD and post about it on the HAMB and not get the moderators undies in a knot is a 49/54 Chev car or up to 62 Corvette. A bit spendy to rebuild and get up to snuff though.
    Hnstray likes this.
  7. Born_too_late
    Joined: Jan 6, 2019
    Posts: 25

    from N. Iowa

    Maybe check out Stoner’s Speed Shop in Hudson, IA. He builds chevy pickups (many on air ride) and might have answers to rim/tire combos.
    hotrodharry2 likes this.
  8. Mr48chev
    Joined: Dec 28, 2007
    Posts: 24,590


    Had to read your first post again. Then I went to a couple of smoothie wheel pages and it doe look like 4 inches is the least backspacing you can get with that wheel.
    When you figure that the 49 box is 50 inches wide, and 4 inchs of back spacing X2 = 8 and subtract that 8 from 60 you end up with 52 inch from inside of wheel lip to inside of wheel lip without tire bulge to fit the 5o inch bed meaning that you have one inch on each side to get tire clearance with a 60 inch wide axle. How much the tire of choice sticks out past the rim gives you your net clearance. My truck is proof that 1/2 inch clearance is not enough as the tire will get into the side of the bed on hard turns. I'd plan on a minimum of one inch and a bit more would be nice.
    Hnstray likes this.

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