Slicks to Leaf Spring Space?

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SSing

SSing

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Would 3" clearance be enough for a set of 10,5 X 29,5 on 15 X 6 wheels with 5" BS?
Maybe 1.5" clearance is enough, incase I decide to shorten rear axel some?
Picture is somewhat miss leading, since this wheel has 4,5" BS and I´m also going to use break drums without fins...
Your experience and advice would be of great help.
Thank you,
Stefan
20170730_140055 8a Slick clear.jpg
 
I have my hand, laying palm flat as clearance around my tires; 28x9x15 mounted on 15x8 rims with 5.5 inches of back spacing.

If I were you I'd look for a wider rim, a 10.5 tire on a 6 inch wide rim will loose a lot of contact area due to crowning of the tire, it also might be a little unstable.

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Yes thanks,
Well the thing is I build this Nostalgia Racer, and looks and correctness is important. They actually ran 6" on these car back than. I will have to compromise with a set of 7" I guess...
20170730_213656 Landy 6inW.jpg
 
JBurch said:
I have my hand, laying palm flat as clearance around my tires; 28x9x15 mounted on 15x8 rims with 5.5 inches of back spacing.

If I were you I'd look for a wider rim, a 10.5 tire on a 6 inch wide rim will loose a lot of contact area due to crowning of the tire, it also might be a little unstable.

View attachment 1715077169

View attachment 1715077170
Click to expand...

Looks quit tight, but those tires are a bit more sturdy I guess... Cool racer...
 
The section width of the tire is the issue...and the section width depends on the width of the rim it is mounted on....short answer is, I don't think you will have sufficient clearance when the tire is mounted.

If your rim is 3" from the spring and IF your section width on your tire is (for example) 10.5", then you will have 2.25" sticking out on each side, so only 3/4" clearance. I would get a wider rim if possible.

I like to have a minimum of a fingers width around the tire, which for me is about an inch (run your hand around the tire and not have it touch the spring).
 
That leaf spring clamp, will eat up a little bit more clearance.
As you showed in post 4 the side wall is eating up a lot of the 3" of clearance.
A wider wheel would actually give you more clearance, side wall clearance (Minimal)
 
Ive ran them with 1 inch clearance to the springs/ clamps
 
flyfish said:
The section width of the tire is the issue...and the section width depends on the width of the rim it is mounted on....short answer is, I don't think you will have sufficient clearance when the tire is mounted.

If your rim is 3" from the spring and IF your section width on your tire is (for example) 10.5", then you will have 2.25" sticking out on each side, so only 3/4" clearance. I would get a wider rim if possible.

I like to have a minimum of a fingers width around the tire, which for me is about an inch (run your hand around the tire and not have it touch the spring).
Click to expand...

Thanks, exactly the info I was looking for. How much the tire build, out of the rim...
And yes, the tire build less with a wider wheel.
 
Thank you all for your input.
I think I will start with 9" slicks and a 7" rim. Also choose a set with stiffer sidewall.
Some say you get a better bite with a slightly narrower rim, but of cause you have to test this and always keep safety I minde.
 
rumblefish360 said:
Correctness in liu of safety????
Click to expand...

No, absolutely not. It will take some time befor I can floor it on all four gears. I´m fully aware of that.
This lady will have no stability chassis wise, what so ever. Torque boxes and a three point Roll Bar is all there is. Not even a motor plate. I know very well she´ll be a hand full, but eventually we will get along fine I´m sure.
Thank you for your concern.
 
SSing said:
Some say you get a better bite with a slightly narrower rim, but of cause you have to test this and always keep safety I minde.
Click to expand...

Nope, and I can't imagine how it could! A wider rim will allow the use of more air pressure while helping to maintain a flatter footprint. More air pressure will also help stability. I run 20-21 lbs in my 9"x30 Hoosier lightweight radial slicks. Bias ply slicks may like less air pressure. (Radial slicks are more sensitive track condition and while they may be a little bit faster, they will not be as consistent under marginal track conditions as bias ply slicks.) Stock class racers are limited to 9" slicks and many launch VERY hard. (i.e.: 1.30 - 1.50 60' times with the front wheels in the air.) Many use 10" rims with the 9" slicks. Some have to compromise due to wheel well & suspension clearance issues like yours. Just because a slicks were called "wrinkle wall" doesn't mean more is better. Excessive wrinkling using narrower rims & lower air pressure can degrade the strength of the sidewall and reduce the slick's effective life. The deformation can also extend to the tread and reduce the contact area. Adding more air on a narrow rim will simply reduce the contact area and increase wear in the middle.

But you are correct about the importance of testing & safety. Each car/combo is different and you have to test to see what combination of air pressure & suspension tuning that particular vehicle will like the best.

As noted by flyfish, tire section width is based on a standard rim width the manufacturer uses for a particular tire size. Wider or narrower rims will alter that section width accordingly.

Have you considered a 3/4" offset kit for the leaf springs. That would be the simplest way to get a little more clearance with re-welding only required for the spring pads. (On second thought, I guess the 3/4" kit wouldn't work in your situation.)

You don't need to change the drums unless you want to save a little weight. They do not cause any clearance issues.
 
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Locomotion said:
Nope, and I can't imagine how it could! A wider rim will allow the use of more air pressure while helping to maintain a flatter footprint. More air pressure will also help stability. I run 20-21 lbs in my 9"x30 Hoosier lightweight radial slicks. Bias ply slicks may like less air pressure. (Radial slicks are more sensitive track condition and while they may be a little bit faster, they will not be as consistent under marginal track conditions as bias ply slicks.) Stock class racers are limited to 9" slicks and many launch VERY hard. (i.e.: 1.30 - 1.50 60' times with the front wheels in the air.) Many use 10" rims with the 9" slicks. Some have to compromise due to wheel well & suspension clearance issues like yours. Just because a slicks were called "wrinkle wall" doesn't mean more is better. Excessive wrinkling using narrower rims & lower air pressure can degrade the strength of the sidewall and reduce the slick's effective life. The deformation can also extend to the tread and reduce the contact area. Adding more air on a narrow rim will simply reduce the contact area and increase wear in the middle.

But you are correct about the importance of testing & safety. Each car/combo is different and you have to test to see what combination of air pressure & suspension tuning that particular vehicle will like the best.

As noted by flyfish, tire section width is based on a standard rim width the manufacturer uses for a particular tire size. Wider or narrower rims will alter that section width accordingly.

Have you considered a 3/4" offset kit for the leaf springs. That would be the simplest way to get a little more clearance with re-welding only required for the spring pads. (On second thought, I guess the 3/4" kit wouldn't work in your situation.)

You don't need to change the drums unless you want to save a little weight. They do not cause any clearance issues.
Click to expand...

Thank you. Some good info here.
About the narrower rim. Some say it to like dig down more and harder in the center, but it is not my experience and it may very well be only in the theory...
Yes, if you look at the first pic, the offset kit is in place, as part of the original feature.
But still, this was how these cars ran back in late sixties, early seventies. And they left hard and ran strong.
I just have to try this out. Starting with as wide slicks as possible on 6-7"rims, making it work at one gear at a time.
 
There is no way, no way the sidewall is going to get wider/fatter next to the spring unless the axle shifts. At speed the tire narrows if anything.
 
For clearance measuring, it is all about the total width (referred to as sectionial width) of the tire mounted /inflated on a particular rim.......not tread width. Most retailers (Summit /Jegs/ etc) have this spec listed.

Example....the 14" (tread) X 32" (diameter) x15" (rims) Firestone Drag 500s for the Flash mounted on 13" wide rims (for mph) have a sectional width of 16-3/4" .

I have 3/4" clearance to the inner wheel well with the above. It was running only about 1/4" with the 14W tire combination that was on it previously.....too close for me.
 
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HemiDenny said:
For clearance measuring, it is all about the total width (referred to as sectionial width) of the tire mounted /inflated on a particular rim.......not tread width. Most retailers (Summit /Jegs/ etc) have this spec listed.

Example....the 14" (tread) X 32" (diameter) x15" (rims) Firestone Drag 500s for the Flash mounted on 13" wide rims (for mph) have a sectional width of 16-3/4" .

I have 3/4" clearance to the inner wheel well with the above. It was running only about 1/4" with the 14W tire combination that was on it previously.....too close for me.
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Thank you for this clarification on section width.
Clearance to leaf spring obviously is not going to be a problem. I might even be able to add another inch to the Back Spacing, (still 2" clearance) and run a 7" rim with the 10,5" slicks, thus keeping the tires under the body...
 
I tend to be over-cautious, so I'd be curious to know what a tire on a narrow rim with low air pressure is doing "at speed" in a situation where it may not be going straight!
 
SSing said:
Thank you all for your input.
I think I will start with 9" slicks and a 7" rim. Also choose a set with stiffer sidewall.
Some say you get a better bite with a slightly narrower rim, but of cause you have to test this and always keep safety I minde.
Click to expand...
A lot of drag racers have been running wider rims than their tires for a long time, it gives a flatter tread pattern. Who ever told u that narrower rims will give better traction is goofy ! If ur going to run 9" slicks, at least run 8" rims. I run 9 1/2" drag radials on 8 " rims, and have to run low air pressure to help make up for it. Radials are a little more forgiving, in my opinion.
 
I run 275 x60-15 ET pro @ 10" wheel
from the Summit site
Tread Width: 9.76 in.
Minimum Recommended Wheel Width: 7.50 in.
Maximum Recommended Wheel Width: 9.50 in.
https://www.summitracing.com/parts/mtt-3754x/overview/

on the 72 Swinger, with a 315 x 60-15 @ 10" wheel

Thread width 11.42 in.
Minimum Recommended Wheel Width: 8.50 in.
Maximum Recommended Wheel Width: 11.00 in.

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002_zpsiaagjdxr.jpg
 
Well the only reason I´m start testing the narrower rim, is be cause this was how the SS/B cars ran back in 1968.
Possibly was the slicks more stable back than, but not much... If it ain´t gonna work, I add an inch at a time. But the fact still is, the Landy Dart pictured in post #4 was running 125 mph on 6" rims 10,5" slicks just over 10 psi. I will start with this combo, and work my way up, an inch at a time, till the ride is "safe".
Thank you for your input.
 
SSing said:
Well the only reason I´m start testing the narrower rim, is be cause this was how the SS/B cars ran back in 1968.
Possibly was the slicks more stable back than, but not much... If it ain´t gonna work, I add an inch at a time. But the fact still is, the Landy Dart pictured in post #4 was running 125 mph on 6" rims 10,5" slicks just over 10 psi. I will start with this combo, and work my way up, an inch at a time, till the ride is "safe".
Thank you for your input.
Click to expand...

You want to kill yourself on the big end have at it.

Fact is the people who make the tires know what's right for them and reinventing it with 1960 ideas does not sound like a sound idea.

I just watched street outlaws last night and seen two cars jumping the guardrails and barrel rolling because they lost the back ends

I would go with two sets of tires. One for show/pictures and another for the track if you going to race it if your dead set on the look

IMHO
 
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fklskv said:
You want to kill yourself on the big end have at it.

Fact is the people who make the tires know what's right for them and reinventing it with 1960 ideas does not sound like a sound idea.

I just watched street outlaws last night and seen two cars jumping the guardrails and barrel rolling because they lost the back ends

I would go with two sets of tires. One for show/pictures and another for the track if you going to race it if your dead set on the look

IMHO
Click to expand...

Actually two sets of tires is a good idea. But again, you just don´t jump in and nail it on all four gears. As always with a new build, you start with first to second gear and than let off. Even take slight turns to see how car reacts.
If nothing works other than 8-10" rims, well, that´s it.
But this build is a piece of history, and I will not give up easy.
Hopefully car is on wheels next summer. But finding 15" steel wheels and old school slicks takes time and I like to be ahead in planning.
Again, thank you for your input.
 
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