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Okay, Professors of Drag Racing... Student needs info


stpracer43

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With so many options (manufacturer/width/profile/circumference) out there, it gets kinda confusing...

 

Eventually, I'll get away from my stock F1s and put on some DRs or slicks.

 

So, here are my questions based on keeping car generally in stock configuration (power/drivetrain/suspension):

 

1) Taller or shorter diameter/circumference than stock? Please explain.

 

2) Stay with 18" wheel, or use smaller (17 or 16") and use bigger sidewall profile?

 

3) Best tire size given the questions above?

 

4) Max tire size that will fit on stock rim?

 

5) Any lighter weight wheels than stock rims?

 

Just a novice racer trying to get educated.

Thanks,

Keith

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Just go to the track and floor it. :)

 

Andy ~ I've got that lesson down real well... Usually results in tire spin, wheel hop, and an average 13.2-13.4 sec time in 1/4 mile!

 

Still trying to learn how to drive my car; will eventually put the useful (go faster) aids on the car, just looking to gain from knowledge of others.

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Hey I'm certainly not an expert but I have tried 18" BF Goodrich drag radials and was not a big fan of them.

 

I switched to 17" Mickey Thompson ET Street tires and at 15 psi I can launch between 4000-5000 RPMs and they stick like glue. Knocked off about 5/10ths from my ¼ mile times. No more wheel spin or tire chips in 1st, 2nd, and 3rd.

 

The part number is 3743 and they are 26X11.50-17LT

 

http://www.mickeythompsontires.com/strip.php?item=ETStreet

 

Good Luck…

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With so many options (manufacturer/width/profile/circumference) out there, it gets kinda confusing...

 

Eventually, I'll get away from my stock F1s and put on some DRs or slicks.

 

So, here are my questions based on keeping car generally in stock configuration (power/drivetrain/suspension):

 

1) Taller or shorter diameter/circumference than stock? Please explain.

 

2) Stay with 18" wheel, or use smaller (17 or 16") and use bigger sidewall profile?

 

3) Best tire size given the questions above?

 

4) Max tire size that will fit on stock rim?

 

5) Any lighter weight wheels than stock rims?

 

Just a novice racer trying to get educated.

Thanks,

Keith

 

 

I am a total rookie at racing, but I've got some thoughts...

 

You want a smaller rim. I'm guessing this reduces rotation mass and effectively lowers your gearing. It also allows room for my next point.

 

You want a relatively larger/taller sidewall run at lower tire pressure. The taller sidewall allows the tires to give a little upon launch so there is less wheel spin. Ever seen pictures of drag cars when they launch? The rim actually twists inside the tire causing the whole sidewall to wrinkle up. This absorbs some of the initial force during launch, allowing the tire to retain grip on the track.

 

The stock rims are pretty heavy. I'm guessing around 35 lbs each? There are a lot of lighter wheels out there. When it comes to drag racing, weight is your enemy.

 

The biggest tire I've seen anyone mount on a stock rim is a 305. Don't know if you can go bigger. I wouldn't want to risk it. There is the option of sending your wheels to a place like WeldCraft and having them widened. I had mine widened to 11" so I could fit a 335 tire on them. A 335/30/18 Nitto will fit without any wheel well modifications. The wider the better.

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With so many options (manufacturer/width/profile/circumference) out there, it gets kinda confusing...

 

Eventually, I'll get away from my stock F1s and put on some DRs or slicks.

 

So, here are my questions based on keeping car generally in stock configuration (power/drivetrain/suspension):

 

1) Taller or shorter diameter/circumference than stock? Please explain.

 

Depends on gears. If you are willing to change wheels at the track I would say a smaller wheel and then the tire height depends on the gearing/ Stock gears or 373's you probably would want a slightly shorter tire height ti increase gearing with stock power. I ran a 26" tall ET Street on a 95 Cobra R knock off rim (for sale mounted and all for $500 plus shipping if you want them) As I approached 800 HP the trap speed was too much for the shorter tire so I have a 28" tall slick on a 15" rim npw (Bogart). As for the 26" ET street it is on a 16x8" rim that bolts right onto the car. I have pulled 1.62 & 1.63 60' times on these.

 

2) Stay with 18" wheel, or use smaller (17 or 16") and use bigger sidewall profile?

 

For drag racing ideally go to a smaller wheel - more sidewall will allow for better hook up and more air pressure adjustment room.

 

3) Best tire size given the questions above?

 

Best is probably a taste thing. One thing to note is if you go with an ET street (or bias ply of any type) and the air is too low or speed to high with radials on the front you can get some butt wiggle/floating feelings. I trapped 133-134 on them and had it but anything under 125 you would be fine. I expect with your power you would be fine and just hook up good as you learned to handle them....I would not suggest driving to the track on these though although they are DOT approved they are not good street tires. If you want to drive to the track and play then look for a drag radial (other wie change tires there). Of the radials the ET street radials seemto be best for hooling up and the Nitto's seem to wear the best from what I have read. I like the look of the lower profile 305/35/18 but many go to the 305/45/18. Both fit the stock rims.

 

Stock driveline makes me want to suggest staying away from slicks. I snapped my axle with them and had to call BVM Performance and get axles, dif, bearings, and a Girdle to build it back.

 

4) Max tire size that will fit on stock rim?

 

Probably not wider than a 305 - some have pushed it wider though I think???

 

5) Any lighter weight wheels than stock rims?

 

Many are lighter. Drag specific wheels like Bogarts are very light but $$$$$. THe smaller rims like my ET streets are on are lighter too but in reality with the stock set up you won't notice a big difference. The difference will be in the hook up for your 60' time and the shorter tire increasing your gear ratio for a little quicker accel. at the track.

 

Just a novice racer trying to get educated.

Thanks,

Keith

 

 

All the above info is what I have picked up over the past 2 yrs that I thought you may be interested in. Feel free to PM me if you have any other questions. I love talking about this stuff and sharing my success and failures so people can learn. It;s a money pit and addictive once you start getting into it...harder to put it all together than you would think too (on the track I mean for a good run).

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Thanks for sharing guys! This is all good info & something I will definitely use...

 

when I can consistently drive my car in it's Fully Stock configuration. Have run a 12.89 once (low 13s mostly) and would like to be able to run 12.8-12.9s on any four out of five runs. then I'd think I'm consistent.

 

Not really looking to go high HP on my car, but do understand if I upgrade some HP I might have to mod the rear as well to improve performance.

 

Appreciate it much.

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Ok.....guess I could give this a shot. I've got "a little experience" with this drag racing thing. :hysterical:

 

1) Taller or shorter diameter/circumference than stock? Please explain.

A taller tire will effectively reduce your gear ratio. Switching from a 26" tire to a 28" tire would be (roughly) equal to switching from a 3.73 gear to a 3.31 gear. A shorter tire has the opposite effect.

 

2) Stay with 18" wheel, or use smaller (17 or 16") and use bigger sidewall profile?

Depends on what tire you want to use. A 17x8 wheel can be used with a tire such as the M&H 275/50R17 drag radial or a 17x9 wheel with the M&H 325/45R17 drag radial. M&H does have a new series of 18" drag radials you could use on a stock wheel too. Here is the link to the page......

http://www.mandhtires.com/store.php?crn=70..._mode=cat_click

 

Personally.....I'd shoot for the 325/40R18 on your stock wheel. You can drive on the street with these easily. No dragging extra wheels and tires to the track for changing. I use the M&H d/r's daily on my GT even in the rain at highway speeds. MUCH safer than a Mickey Thompson ET Street.

 

3) Best tire size given the questions above?

See above answer.

 

4) Max tire size that will fit on stock rim?

Probably the M&H 325/40R18.

 

5) Any lighter weight wheels than stock rims?

That's where you're going to spend some money! The only aftermarket drag wheels that fit over these brakes will be either Bogart or Holeshot. Either of these will set you back about $1500 for the set of four.

 

I hope that helps a bit. Let me know if you have any further questions.

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I started out with Nittos and got about 10K miles out of a set. They hook better than stock but are no good in cold weather and if you are pushing 700+RWHP then you will be limited. These were on stock rims. Then I got a set of MT ET Street Radials II 305/45/18. These are tall tires and my a$$ was way in the air. Still have them on the car. Tire height is 28.75 inches, which is a couple inches taller than stock and possibly more than the Nittos.

 

Today I got a deal I couldn't pass up. New set of 15 inch Bogart D-10s with a new set of MT ET Street Radials for $500 cash. The wheels are about $450 each plus $209 each for tires plus shipping so probably $1350 worth of gear for $500! SWEET. These are my track tires and rims for now but considering a front set of skinnys as well. These rims probably weigh 20lbs less than stock. One other thing, you can not fit 15 inch rims on the back of the GT500 without bending the brackets for the sway bar and getting a sway bar relocation kit. I got mine from BMR. Here are a few pics of the same tire / rim combo I tried on that a friend of mine had some time ago. I can't believe I found the same setup!

 

Oh - these tires are 1.6 inches wider than stock and probably about the same height. The MT ET Streets that are 45/18s are 3/4 taller so I would not recommend them. Also I was never sure about the difference in MT ET Streets and ET Street II tires but the ET Streets appear to be for more dedicated drag use while still being DOT approved. They boast special side wall design for better traction and a lesser tread as well. I had the ET Street IIs before. These are an inch wider and should hook better so I welcome the first chance to try them out!

 

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MrFarmDog... Those look pretty sweet on your car!

 

The consensus I'm reading is go with smaller wheel but a larger tire for more sidewall, to get more deflection on launch, and therefore more bite.

 

Time to start saving my pennies!

 

Thanks,

Keith

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MrFarmDog... Those look pretty sweet on your car!

 

The consensus I'm reading is go with smaller wheel but a larger tire for more sidewall, to get more deflection on launch, and therefore more bite.

 

Time to start saving my pennies!

 

Thanks,

Keith

 

 

If you guys are gonna start trying to hook hard I'd upgrade the Dif. cover to a girdle at the very least. It may not have saved me but ir would have helped a lot and for about $200 it is a really good way to start beafing up that rear end. Looks better too. I put one on after I snapped my axle and was happy to be able to get such good prices from BVM Performance. They saved me some $ in that rebuild.

 

Here is the girdle and the broken axle still in the dif. (which also had to be replaced due to a cracked housing).

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On the cheap end of the spectrum, you'll find my solution. My '07 GT is supercharged, so traction is hard to find with my factory 18 inch wheels/tires. I bought a cheap set of four 17x8 gray bullitt wheels (for race days) from a guy with an '06 V6 Mustang. Kept the skinny stock tires on the front pair and installed a pair of 275/40/17 BFG drag radials on the back pair. At the track, I heat them up in a second gear burnout, then launch at 4,800 rpm's with absolutely no slip or spin at all. Car runs consistent 12.30's at 111+ in the 1/4 mile as configured. Here's a couple pics...

 

RaceReady004.jpg

 

RaceReady014.jpg

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  • 3 weeks later...
On the cheap end of the spectrum, you'll find my solution. My '07 GT is supercharged, so traction is hard to find with my factory 18 inch wheels/tires. I bought a cheap set of four 17x8 gray bullitt wheels (for race days) from a guy with an '06 V6 Mustang. Kept the skinny stock tires on the front pair and installed a pair of 275/40/17 BFG drag radials on the back pair. At the track, I heat them up in a second gear burnout, then launch at 4,800 rpm's with absolutely no slip or spin at all. Car runs consistent 12.30's at 111+ in the 1/4 mile as configured. Here's a couple pics...

 

Five-Oh ~ Thanks for the info. Those are some great times you're running. Have been thinking about a 17 inch wheel for the rear and seeing what I can do.

 

I've managed another 12s run (12.806 @ 111.89) but still not consistent enough to get two in a row or 4 out 5. Thinking I've worn out the GOOD on my stock F1s.

 

Appreciate it!

Keith

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I took my BJ Shelby GT (automatic - never misses a gear) to the track at Bandimere. This was my very first time ever, and I missed my chance to have a coach to show me the ropes so I just did it. We got two practice runs and then it counts for real.

 

The first time up I had a horrible reaction time (.8 sec), but I managed to get 13.6 (and had to get a helmet and fire jacket because I had a 'vert under 14). The next two runs I cut my reaction time to <.2, but my times got worse because my tires wouldn't hook up. The first time I ran I was the 10th or so in the lane and there was very little tire goo. Each time I ran I was overpowering the rear end and spinning out so I let off the accel. The short distance times got worse each time, but the 300' marks were all the same and slightly improving. I think this car is a solid 12.8-13.

 

The answer to your question is:

 

More road contact. High horsepower needs surface area. Wider is better.

 

Traction depends on grip. Sticky is best.

 

I'm going back in the spring (with the SGT, not the Cobra, yet) with some cheap rims and Micky Thompsons. With a vert if I get <13.0 (12.999999) they will toss me anyway without a functional roll bar, so I'll retire happy :).

 

Good luck!

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