Who's running 15" drag wheels?

Kurt K

Kurt K

SCCoA Member
I'd like to run 15" drag wheels because of the wider selection of tires, but after using David Neibert's 16 x 8.5 rear Bogarts for test fitting, it looks like the widest 15" wheel that will fit is 8" due to the upper control arm....well, unless I wanted the wheels to stick out some. With that said, I tried using David's Bogarts last fall, but I actually lightly rubbed the fender with the 27" tire when driving around the block to load the car on my trailer.

If you have 15" drag wheels, what is the backspacing and is your car lowered?
 
I never used drag wheels, but I did use the 15" LX wheels. I used 28x9" tires and I didn't have any problems with rubbing. My car isn't lowered, though.
 
I've run 26x10.5 ET Streets on a 15" LX wheels on my lowered 93 SC. The fender lips have been rolled on that car though.

I do want to get a wider wheel some day, but to stay 15" it'll likely be something custom. It's become obvious that 15" wheel size is where to be to get decent sizes for drag tires.

the biggest issue with a tire that size on the lx wheel is that at the low pressures that hook the ET Street, the side walls just don't give enough support to feel confident at the end of the track for some people. Running just over 100mph at the at the finish line, I have noticeable wiggle going on with my combo.

the picture shows how the tire fits with the wheel at launch.
 

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kurt,

i have 15x8 with 5.5 backspace on my welds. i have a 26x10 et drag tire and yes the car is lowered. h&r with an airbag in both springs.
 
I've been running a 26 x 9.5 x 16 quick time pro on stock SC wheels for years now. I know this isn't info you're looking for but as Mike stated above, I experience some extreme mushy/swaying motion on the track. It's an unsettling feeling crossed the traps at 110+. I'm wondering if the issue gets worse when running a 15" wheel due to a larger sidewall. I chose the 16" option only because the stock SC rim is wider than the 15" LX.

1018DSC_3111.jpg
 
fastsc92 said:
I've been running a 26 x 9.5 x 16 quick time pro on stock SC wheels for years now. I know this isn't info you're looking for but as Mike stated above, I experience some extreme mushy/swaying motion on the track.
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It's the bias ply tire construction, low air pressure, and narrow wheel allowing side swaying as the push from engine torque drops off, unloading the sidewalls of the tire. Radial tires do much better, of course more power would also help.
 
Mike8675309 said:
It's the bias ply tire construction, low air pressure, and narrow wheel allowing side swaying as the push from engine torque drops off, unloading the sidewalls of the tire. Radial tires do much better, of course more power would also help.
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I understand that's the nature of the bias ply construction, but I'm wondering if it gets worse with a taller sidewall, such as with a 15" rim with the same overall diameter.

I've also been told that it is because I was running radials in the front, bias ply in the back. Luckly, it doesn't happen too long, but at any momment I feel like the rear end is going to wash out behind me. I just let it do its thing and try not to correct anything. I'm running 18psi BTW.
 
It's the fault of the suspension. The stiff springs and shocks keep most of the energy in the tires. Things like removing the front sway bar, running a softer spring/shock, or a bias ply front tire will help.
 
neverfastenough said:
Fast92sc, I use the same tires, what PSI do u commonly run?
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anywhere between 15 and 18psi. I've run them lower, but didn't see a reduction in 60' times, but the lower pressure resulted in more high speed instability. Best 60' times are high 1.6x's, most commonly I run low 1.7x's. Not great times, but they really bite, and those tires are the best size for stock wheels. Next time I head to the track I'll be running a two step, so it should help with my launches....if the clutch holds up this time...
 
fastsc92 said:
anywhere between 15 and 18psi. I've run them lower, but didn't see a reduction in 60' times, but the lower pressure resulted in more high speed instability. Best 60' times are high 1.6x's, most commonly I run low 1.7x's. Not great times, but they really bite, and those tires are the best size for stock wheels. Next time I head to the track I'll be running a two step, so it should help with my launches....if the clutch holds up this time...
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I'm curious about why you think using a 2 step with a positive displacment supercharger will help with lauching the car. I know why it works on a turbocharged motor or even a supercharged motor with an automatic w/trans brake, but don't see how it would help with a supercharged manual transmission car.

David
 
would be nice to just hold your foot on the floor and then release the clutch, rather than finding a rpm and trying to hold it there.
 
I used to run 26x11.50 ET Streets on stock SC wheels and when I added my new converter, they would spin badly, really badly. I decided to try 27x10.50 ET Streets on stock SC wheels, since I've heard that a taller tire will typically hook better (more contact patch). No matter what pressure I run, they still spin; but I am finally getting back to the mid-1.7x / high-1.6x range while spinning. Anything below 15 psi starts getting squirrly on the big end. I know running a wider wheel would fix some of the squirrliness.

I want to run a DOT tire and there are becoming fewer choices in sizes for 16" wheels. 15" wheels will give a better selection. If it wasn't for the upper control arm and E-brake cable, I'm pretty sure you could fit a 10" wide wheel in there.
 
fastsc92 said:
I understand that's the nature of the bias ply construction, but I'm wondering if it gets worse with a taller sidewall, such as with a 15" rim with the same overall diameter.

I've also been told that it is because I was running radials in the front, bias ply in the back. Luckly, it doesn't happen too long, but at any momment I feel like the rear end is going to wash out behind me. I just let it do its thing and try not to correct anything. I'm running 18psi BTW.
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Wow 18 psi. You would hate my car running mine at 12-14 psi. I'm more afraid of locking up the front tires on the top end. I'm leaning towards bigger rear brakes this winter. It sways a little but nothing I can't handle.
 
On a 5-speed, you can't put any load on the motor to build boost prior to launch. It's more efficient to use power to move a car as opposed to inertia, in respect to tire spin and acceleration. If you use a 2-step, you'll see a more consistent, controlled, and quicker 60 foot.
 
David Neibert said:
I'm curious about why you think using a 2 step with a positive displacment supercharger will help with lauching the car. I know why it works on a turbocharged motor or even a supercharged motor with an automatic w/trans brake, but don't see how it would help with a supercharged manual transmission car.

David
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I'm not looking to build boost, but I find it difficult to get consistant launches using a manual-launch method. I've gotten pretty darn good at it, but it would be nice to hold the pedal half-way down (full throttle will activate the nitrous), and be able to leave once the clutch is released. The way I have it wired now is that I use the line lock button and the clutch button at the same time. This is a one time activation. Once activated, I can release the line lock button. To disengage the two step, all I have to do is release the clutch. The two step wont re-engage unless I use both buttons again. I haven't had a chance to try it out yet, but I think it'll work well. I can post the wiring for it if anyone is interested.
 
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