47-59 Wheel backspace and fender clearance

[bowt1ed]

Looking for insight regarding suitable, minimum clearance between wheel/tire and rear inner fender lip on my 57. Currently sizing American Racing's VN425 and would like to go with 20x12 on rear. Goal is to have as minimum backspace as feasible to maintain a deep dish look. Running a slightly narrowed 10 bolt with No Limit 4 link and bedsides cut out for tubs, so inside and top aren't an issue for clearance. I have 7 inches from mating surface to inner fender lip, so a 12" (13" overall) with zero offset should give me 1/2" clearance (to wheel). Plan on running @ 315/40 ish as not to extend tire width past wheels. Just not sure what a feasible space between wheel/tire and inner fender lip should be. Is 1/2" too little? Anyone running a similar set up/look, please share your experience. Thanks, Jim

[mr48chev]

Suitable minimum clearance is what you personally are comfortable with.

If the truck is going to be low enough so the top of the tire (especially on wide wheels and tires) doesn't drop down far enough to be readily removable it can be a challenging issue.

We had to take the shock loose and then take my little bottle jack between the axle and the frame to push the axle down far enough to get the tire off my buddy's rig on the side of the road on a road trip to a rod trot one time so we could put my spare on it.

I've had to deflate tires to get them in under the fenders and air them up on a number of lowered rides or rigs with wide tires over the year. Real common in the 70's when guys including myself ran N 50 Firestones.

I'd have to measure but have around an inch on the outside on my 48 and never rubbed on the outside but have a half inch if I am lucky on the inside and it rubbed a lot.

I think I posted a couple of tire size comparision calculators the other day but here they are again.

https://www.tacomaworld.com/tirecalc

https://www.discounttire.com/learn/tire-size-calculator

This one I am starting to like better as it gives you two views of the tires side by side. https://tiresize.com/comparison/

Those will let you know how wide of section width a tire has and how tall it is.

[jweb]

My 51 has 1/2" clearance on either side to the tire. If you're saying 1/2" to the wheel that seems too close.

Until I added a sway bar it would rub on the bedsides around corners. Even with the trailing arm/ coilover suspension setup. Since I added the sway bar I haven't had any issues but I'm also not very aggressive.

[bowt1ed]

Originally Posted by mr48chev

Suitable minimum clearance is what you personally are comfortable with.

If the truck is going to be low enough so the top of the tire (especially on wide wheels and tires) doesn't drop down far enough to be readily removable it can be a challenging issue.

We had to take the shock loose and then take my little bottle jack between the axle and the frame to push the axle down far enough to get the tire off my buddy's rig on the side of the road on a road trip to a rod trot one time so we could put my spare on it.

I've had to deflate tires to get them in under the fenders and air them up on a number of lowered rides or rigs with wide tires over the year. Real common in the 70's when guys including myself ran N 50 Firestones.

I'd have to measure but have around an inch on the outside on my 48 and never rubbed on the outside but have a half inch if I am lucky on the inside and it rubbed a lot.

I think I posted a couple of tire size comparision calculators the other day but here they are again.

https://www.tacomaworld.com/tirecalc

https://www.discounttire.com/learn/tire-size-calculator

This one I am starting to like better as it gives you two views of the tires side by side. https://tiresize.com/comparison/

Those will let you know how wide of section width a tire has and how tall it is.

Thanks!

[bowt1ed]

Originally Posted by jweb

My 51 has 1/2" clearance on either side to the tire. If you're saying 1/2" to the wheel that seems too close.

Until I added a sway bar it would rub on the bedsides around corners. Even with the trailing arm/ coilover suspension setup. Since I added the sway bar I haven't had any issues but I'm also not very aggressive.

Thanks!

[dsraven]

without going through a thread to see your truck and suspension mods I would recommend that you run the suspension through a full top to bottom cycle and take some dimensions on both sides of the wheels/tires that you have on it now. do both sides of the truck too, just to cover all the bases. I say this because, depending on how the suspension is built, the rear axle may have side to side movement built in depending on what style of suspension you have and how tight any bushings are. if you have a panhard bar to locate the axle laterally, and it is a short one, then the lateral movement will be more than if the bar is a long one. if that same bar sits at an angle at ride height then the lateral movement will be more in one direction than it will in the other direction (suspension up versus down) simply due to the geometry and how the bar ends make an arc around the frame mount.
anyway, long story short, we can't tell you what clearance to use until we know what you have for dimensions as the suspension travels. you could remove the wheels and bolt on a length of angle iron across the wheel mounting surfaces, both sides, and then run the suspension through a full sweep as you take dimensions from the angle iron to the inner box side and the inside edge of the fender lips,both sides. that will tell you the size of the box you need to work within, so the fattest your tires can be, and also what your positive or negative offsets can be.
speedway motors has a wheel fitment tool for offset and backspace, they have a youtube showing it and how it works. just google it for a demo.
I remember a lot of guys that had tire rub with the N50 tires, especially on one side as the vehicle went over a bump. lots of guys just thought the suspension was worn a little or the axle wasn't quite centered. that may have been the case but it also was partially because the rear end was jacked up to allow the N50's to fit, so the suspension panhard bar was already arced down and pulling the axle a little to one side. then as the suspension went up, over a bump, the panhard bar arced the axle back more to the other side and those fatties would rub on that side.

[dsraven]

https://www.speedwaymotors.com/Wheel...up,485869.html

[bowt1ed]

Thanks! I did verify my static measurements with a Percy Wheelrite tool, but not under simulated travel. No Limit's 4 link panhard is long (almost frame rail to frame rail) with a very slight angle. I think I may err on the side of caution and just give it a bump in backspace for new wheels. Thanks again for the info.
Cheers, Jim

[dsraven]

another thing to do is put it on stands on the frame so the axle and suspension are hanging and then see how much side to side movement you have. sometimes it is surprising how much give rubber or urethane bushings can have as a collective group.

[bowt1ed]

Another question - any reason why the lower coilover mount can't fit within the wheel opening? This current wheel is an 18x8. With a 20x12 the lower part of the mount would fit slightly within the inside of the wheel. I can't think of any issue with it though. Am I missing something?

[bowt1ed]

Sorry for the sideways pics...

[dsraven]

here is a link to a calculator I have used a few times. it can be handy, especially for front end because it includes scrub radius, but works for rear as well.
https://www.wheel-size.com/calc/
whatever fits into the wheel well for other parts besides tires and wheels is up to you, as long as they don't interfere with the body parts and, obviously, the tires and wheels.

[dsraven]

sorry, I was thinking you were wondering about fitting suspension parts inside the wheel opening or inner fender area behind the wheel. I get it now, your lower shock mount is gonna be inside the back of your wheel dish. prolly be fine as long as you test run it through a full suspension swing to ensure no problems with rubbing etc. if you have a problem with suspension parts breaking then it wont matter much if they are out in the open or hidden inside the wheel dish a bit, your mind will be busy figuring out how not to crash either way. you may wanna look into tieing up your park brake xcable so it doesn't rub the tire, but you obviously aren't done yet so you prolly have that on the list of things to do.

[bowt1ed]

Thanks. Yes, just wondering if there would be any concern, that I was missing, with the lower coilover mount being within the wheel dish. Since it is static/solid, I wouldn't think so. Yep, I still need to cut more on bedside openings and affix parking brake cables closer to the frame rails after fitting new wheels. Thanks much, Jim

[_Ogre]

My rear wheels aren't as bad as mr48 on TRUK, but I do have to jack up on the frame and wiggle the wheel out from between the fender and the brakes. That is with ten inch tires

[dsraven]

yeah, maybe keep a couple of adjustable wrenches in with the spare tire so you can disconnect the coil over and then when the truck is jacked up, to change a flat, the wheel will be allowed to drop enough to get it off the axle and out past the fender. somebody on here built a frame and included a jack mount on the frame, not a bad idea for low slung stuff. look for a nearby curb to drive up onto so you can get the jack under it when a tire is flat (never happens in a good spot so thats a dream, lol)
or get a membership for the car club that has towing on a deck truck included, haha. sometimes the dragging it up onto the deck also causes damage too though. maybe tow dollies are better for some stuff.

[skip99]

Move the shock mount in a little…

[iceman4]

Great info from previous posts. I can't speak to your tire sizes . I installed the No Limit 4 link last year on my 57. I have a gen 1 camaro rear, aprox. one inch narrower than stock task force rear, no tubs, the 265/70r15s are 10.4'' wide. approximately 1/2" tire clearance between outer and inner fender. As stated if the panhard bar is installed close to level the rear has very little side to side
movement with this setup. No problems so far. The coilover mounts look like they will work OK with your 20" wheels, I'm using 15'' wheels so I mounted mine as far as possible from the wheel, coilover mount is welded against the 4 link bracket. Looks good best of luck! Sorry for the sideway pictures.

[bowt1ed]

Originally Posted by iceman4

Great info from previous posts. I can't speak to your tire sizes . I installed the No Limit 4 link last year on my 57. I have a gen 1 camaro rear, aprox. one inch narrower than stock task force rear, no tubs, the 265/70r15s are 10.4'' wide. approximately 1/2" tire clearance between outer and inner fender. As stated if the panhard bar is installed close to level the rear has very little side to side
movement with this setup. No problems so far. The coilover mounts look like they will work OK with your 20" wheels, I'm using 15'' wheels so I mounted mine as far as possible from the wheel, coilover mount is welded against the 4 link bracket. Looks good best of luck! Sorry for the sideway pictures.

Thanks for info!