Quickest/fastest quarter mile on 15 inch "cosmetic" all season tires like BFG T/As (etc)?

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MRGTX

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Tires are everything...with a 2wd car, it is pitifully easy these days to run out of tire LONG before you run out of power. That applies to us in particular since so many of us have V8s and 15" (or smaller) wheels.

As we have talked about many times, outside of straight-line-only drag tires, there simply are no options for 15" performance tires taller than 24.5" OD (which almost all of us need for our cars).

That said, a lot of us are stuck on BFG T/As, Cooper Cobras, M/T Sportsman ST, etc. In addition to the 400+ treadwear ratings, these tires are S Speed Rated (112mph) or T speed rated (118mph), either of which is too close for comfort (IMO) for what a basic 400ish hp car would be running in the quarter.

So what's the best you've done on this cheesy class of tires? What's the best you've seen?

Would you even show up to a drag strip with these tires? Do your cosmetic all seasons give you pause when out driving like a hooligan?
 
Ran 12.8 with Cooper Cobras on my old smallblock Dart 5-6 years ago. 360, one X and one J head, Mopar .508 cam, 904 manual valve body with 3:23 gears

dartr.jpg
 
14.0 @ 95 mph all day long in my 70 Dart, mild 360/727/3:23 on 245/60 R14 Cooper Cobra tires. Swapping a pair of 235/60R15 BFG drag radials netted 13.8 @ 99 mph.
 
11.8 @ 112 the old Manhandler H60x 15 in 1980. lol
71 Charger with 440
 
Take a look, if you haven't seen them already, the cars that are running in the F.A.S.T. classes. These guys are running low 10s high 9s on factory type 7" wide bias ply tires!
Pretty awesome to watch too.
 
Take a look, if you haven't seen them already, the cars that are running in the F.A.S.T. classes. These guys are running low 10s high 9s on factory type 7" wide bias ply tires!
Pretty awesome to watch too.

How can this be? I know the rules about the tires but something doesn't add up.
Firestone Wide Oval (the tires that came from the factory on the fastest cars in F.A.S.T. racing) are "S" rated which means that they're only approved for 112 mph. Many cars are running well past this. The fastest cars in this class are evidentially running ~140mph! No way in hell would I go 140mph on a tire that isn't made to go faster than 112.

Are these people absolutely insane or is the rating known to be falsely low? It's one or the other...
 
How can this be? I know the rules about the tires but something doesn't add up.
Firestone Wide Oval (the tires that came from the factory on the fastest cars in F.A.S.T. racing) are "S" rated which means that they're only approved for 112 mph. Many cars are running well past this. The fastest cars in this class are evidentially running ~140mph! No way in hell would I go 140mph on a tire that isn't made to go faster than 112.

Are these people absolutely insane or is the rating known to be falsely low? It's one or the other...

Just because the tire is rated for 112MPH doesn't mean it's going to immediately explode at 113. I got a reckless driving in my Charger way back when I was still young and immortal. In the comments box of the ticket was written "radar indicated 146MPH". That's 34MPH higher than the speed rating of my tires, and I'd been going that fast for a minute or two. Nothing happened. I'm still here.

Do I recommend such behavior? Absolutely not. Have I been that silly on more than occasion? Years ago, yes. I've never suffered a speed-related tire failure but I'm sure others have.

I believe the speed rating is based on a sustained speed, i.e. "travelling at a constant 112MPH" rather than "Never exceed this rating ever or you will die." I could be 100% wrong about that. I do know that it's mostly a CYA measure for the tire companies to limit their liability. Regardless, those F.A.S.T. competitors are above the speed rating for only a few seconds.
 
How can this be? I know the rules about the tires but something doesn't add up.
Firestone Wide Oval (the tires that came from the factory on the fastest cars in F.A.S.T. racing) are "S" rated which means that they're only approved for 112 mph. Many cars are running well past this. The fastest cars in this class are evidentially running ~140mph! No way in hell would I go 140mph on a tire that isn't made to go faster than 112.

Are these people absolutely insane or is the rating known to be falsely low? It's one or the other...
They re-produce these tires, so I'm sure they are rated better, & if you've seen these cars, they are like show car condition, so I doubt they would risk running the tires if they thought they couldn't handle the speed. Just my opinion.
 
Take a look, if you haven't seen them already, the cars that are running in the F.A.S.T. classes. These guys are running low 10s high 9s on factory type 7" wide bias ply tires!
Pretty awesome to watch too.

And those tires have had sticky compounds applied to them..
 
F.A.S.T. means "factory appearing, stock tires", which translates to "looks stock, and runs stock sized tires", but is anything but stock. Still impressive to see what some of these cars can run, but they are far from "showroom stock".
 
How can this be? I know the rules about the tires but something doesn't add up.
Firestone Wide Oval (the tires that came from the factory on the fastest cars in F.A.S.T. racing) are "S" rated which means that they're only approved for 112 mph. Many cars are running well past this. The fastest cars in this class are evidentially running ~140mph! No way in hell would I go 140mph on a tire that isn't made to go faster than 112.

Are these people absolutely insane or is the rating known to be falsely low? It's one or the other...
That speed rating is for continuous use, like for an hour or two across Montana. They are perfectly safe for 130 or 140 mph for three or four seconds. (Unless, of course, the have been softened to silly putty).
T/A radials turned my low 11 second car into a mid 13s car. (Had to make a points race, and one slick was flat.)
I would not even bother taking a car to the track on any of the above mentioned cosmetic tires.
 
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Just because the tire is rated for 112MPH doesn't mean it's going to immediately explode at 113. I got a reckless driving in my Charger way back when I was still young and immortal. In the comments box of the ticket was written "radar indicated 146MPH". That's 34MPH higher than the speed rating of my tires, and I'd been going that fast for a minute or two. Nothing happened. I'm still here.

Do I recommend such behavior? Absolutely not. Have I been that silly on more than occasion? Years ago, yes. I've never suffered a speed-related tire failure but I'm sure others have.

I believe the speed rating is based on a sustained speed, i.e. "travelling at a constant 112MPH" rather than "Never exceed this rating ever or you will die." I could be 100% wrong about that. I do know that it's mostly a CYA measure for the tire companies to limit their liability. Regardless, those F.A.S.T. competitors are above the speed rating for only a few seconds.

All good points here (and nicely done with your Charger!! :D ). From what I know about how tires fail, I believe you are completely correct about the sustained speed (and heat) being part of the equation but this is not how the DOT speed rating is assigned. It's purely based on a maximum speed value.

Obviously, these drivers exceed these speeds at every event and the tires don't explode. That doesn't make me stop scratching my head. The NHRA safety rules are waaaay conservative. You can't even run down the drag strip with your damn windows open! Plenty of items rely on DOT approval (especially brake components)...You need a roll bar at a 11.49 (well within the range of many STOCK street cars), you need a drive shaft loop if you have slicks, you can't wear white pants before Memorial Day, etc.

Given all that, isn't nearly unbelievable that the class rules require that you run a tire that will be vastly exceeding its DOT certified safety rating?

I'm not arguing with the fact that this is the rule. It just baffles me...even more than the amount of traction that they put down.
 
They re-produce these tires, so I'm sure they are rated better, & if you've seen these cars, they are like show car condition, so I doubt they would risk running the tires if they thought they couldn't handle the speed. Just my opinion.

I hear you but unless the manufacturer says so, you can't count on them being better than the originals. Besides the "S" speed rating is for the current releases of these tires.

F.A.S.T. means "factory appearing, stock tires", which translates to "looks stock, and runs stock sized tires", but is anything but stock. Still impressive to see what some of these cars can run, but they are far from "showroom stock".

Yeah but the rules are pretty straight forward when it comes to tires:

14.01 Wheels must be correct*, including correct* diameter, width and material.
Note: Width may be upgraded to a maximum of 6”, if the correct* wheel is narrower than that. Reproduction wheels OK.
14.02 All 4 wheels and tires must be same size.
Exception: Mopar TA Challenger came from factory with G-60’s on rear and F-60’s on front.
14.03 Original equipment reproduction bias-ply tires only. No soft compound tires of any kind are allowed.
Retread tires are not allowed. Any car is allowed to upgrade to a maximum size tire of G-70 of the correct* wheel diameter.
All cars that were originally available with a 60 series tire can upgrade to a maximum size of G-60 tire of the correct* wheel diameter. ...
 
only 14" but seems to still be basically what your asking about.
The difference with non-drag tires is mostly on getting out of the hole. That's assuming it was geared for 1/4 mile - which mine is not.
2020 Small Block Penalty Box Race Sign Up
 
In my experience you will have the best luck with a bias ply. I have e70 Polyglas on the front of my gts and m&h muscle car bias plys on the back. The 235-60-14 m&h used to have some tread lol. They are almost worn out after 100s of smokey four gear holeshots, a glovebox stuffed full of time slips and countless errands around the valley (4 miles to the market, 10 miles to town).

It's too subjective when it comes to opinions on how the car handles. I removed the front sway bar and installed QA1 stocker stars shocks. The rest is OEM as delivered from Chrysler. I have no problems driving the car 45 minutes about 35 miles) to the track and not many roads in this area are straight or smooth (chip seal).

The only caveat is to pump up the tires before you drive home. I drove out on the highway with 11lbs one night. Car felt a little mushy in the roundabout and when I pinned the throttle coming out of it the handling was akin to a deep v hull not yet on plane. Not advised!
 
Really, how fast do you want to go? I’m at 11.39 at 117 1.60 60’ on F70-14 redlines and I’m slow. Heat kills tires, no time for heat to build up in a 1/4 mile run. The tires are not soaked, it was tried in the past. No one does it that I know of. They are the same tire you would buy from Coker. Coker WILL NOT build you a stickier set. Slicks aren’t speed rated. All that aside, I bought a set of M&H DOT musclecar 14” bias plys for dragweek. They wouldn’t let you run a street tire. Pretty sticky. Only ran them on the track. They are short 25” but that is 14” wheel. 15’s who knows. Swapped back to my redlines for the street.
 
Another factor I haven't seen mentioned yet about the speed rating is in relation to weight load and tire pressure. You can read on the sidewalls of modern tires "Inflate to XX psi MAX at YYYY lbs max load". Our A-bodies are pretty light and typical 9+ inch-wide 60-series tires can usually handle at least 1.5x (probably closer to 2x) the load that our cars put on them.

That's why you can technically inflate a tire well over its "max" rating and it won't explode... unless you run it on a heavy C-body or truck and cruise near the max speed rating for a decent amount of time (much more than it takes to run down a 1/4-mile). Running at lower pressure heats up the tire faster due to more tread and sidewall deflection as it rotates but again over the course of 10-15 seconds that's not a whole lot.
 
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