Drag racing experience - 15 or 17 inch rear wheels?

This may seem crazy, but given all the complications (I know there are varying opinions) with using an MT82 with a 3.73 rear end as a street and strip car, I started looking around. I found an exceptionally clean 2014 GT Premium with the Brembo package and a 6R automatic. The package came with 19x9 inch wheels and 255/40R19 Tires (27.1"). The car is essentially stock, with the 3.15 rear end, which in combination with the 4.17 first gear is fairly low (13.14).

The Race Star 92 Drag Star Polished Wheel; Rear Only; 15x8; Direct Drill with Mickey Thompson ET Street S/S Tire(275/60R15) would be approximately 28 inches tall. Would that setup in the rear, and the stock tires in the front be acceptable, or is that too much diameter deviation for the ESC? A 275/50R15 would have a diameter of about 26.4 inches. Would that be acceptable, and perhaps provide a better launch due to the lower effective gearing?

Thanks in advance!

I run stock fronts and a 29" tire in the rear on the street. I use a 28" tall tire at the track. 15x10 race stars with Hoosier QTPs. I have driven to the track at like 28 psi and then drop it down to like 12-14 psi at the track. On the way home I just stop at the truck stop and fill them back up again for the ride home. Not advisable but doable. I have also swapped my tires at the track and chained them to a light pole in the pits. Being that you have a bit of a drive I would opt to swap them at the track if you go with a DOT approved slick. Otherwise the ET streets are the best your gonna do. I have driven many a mile with radials up front and bias-ply in the rear without any issue but I wouldn't expect much from handling corners. But definitely 15' rims are the way to go.

Red-Candy-Metallic said:

This may seem crazy, but given all the complications (I know there are varying opinions) with using an MT82 with a 3.73 rear end as a street and strip car, I started looking around. I found an exceptionally clean 2014 GT Premium with the Brembo package and a 6R automatic. The package came with 19x9 inch wheels and 255/40R19 Tires (27.1"). The car is essentially stock, with the 3.15 rear end, which in combination with the 4.17 first gear is fairly low (13.14).

The Race Star 92 Drag Star Polished Wheel; Rear Only; 15x8; Direct Drill with Mickey Thompson ET Street S/S Tire(275/60R15) would be approximately 28 inches tall. Would that setup in the rear, and the stock tires in the front be acceptable, or is that too much diameter deviation for the ESC? A 275/50R15 would have a diameter of about 26.4 inches. Would that be acceptable, and perhaps provide a better launch due to the lower effective gearing?

Thanks in advance!

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Did you end up buying the car? For what it is worth at this point in the conversation: Track prep is going to be your deciding on any tire you decide to run. When my car was a stick, it would not hook up on radials unless I ran a very prepped track. Bias ply tires were much better. I have driven to the track on bias ply tires on the rear and radials on the front. The radials are much better for the trip back and forth but the bias ply tires were not that if you drive cautiously.
I have these rims https://lmr.com/item/SVE-10071652H/Mustang-SVE-Drag-Wheel-15X10-Gloss-Black-05-14
When I had the stock rear sway bar, I had to relocate it.

Thanks for responding, and for providing the link to the wheels.

I did end up buying the car. The car has about 59,000 miles on it now after driving it from Massachusetts to Florida, where the car will stay. The car ran great, and all the gauges remained in the normal range, as well as getting 24.5 MPG doing 70-80 MPH the whole way. The only aftermarket parts are the Legato axle-back exhaust. On June 29, I managed to get 12 passes in at Bradenton Motorsports Park (FL) on the stock AS 255/40R19 tires. Having the 6R80 transmission, the car ran consistently, and nothing overheated (temp ranged from 92-82 degress). My best run was a 13.11 ET at 106.82 MPH and the DA was about 2500 ft.

On a separate note, I am back in Massachusetts for the summer, and I have made my way up to New England Dragway a few times, with my 2012 GT with the MT-82 and the 3.73 rear end. I still have the factory spec 235/50R18 AS tires on it, so I am launching barely off idle for the most part. This is the first time that I have experienced the dreaded 3rd gear lockout, and it has ruined most of my runs. Last night I did manage to run a 13.14 ET at 108.87 MPH on my second to last run (DA 2038). This was encouraging, as at least it showed me what was possible with 3 clean gear changes. Earlier, I did have a 1.97 60 ft but ended up getting locked out of 3rd. I kept telling myself to shift around 6000 RPM on the 2-3 shift, but I never managed to avoid 6800 RPM or so. Just poor discipline on my part. I have the stock shifter with the Barton 2 post bracket, but I have ordered the Barton shifter.

Given my approximately 180 or so round trip to New England Dragway with the MT-82 car, I am considering changing the rear wheels at the track. I know that bias ply tires (M/T ET Street R) would be the best solution for the manual transmission, but I am somewhat anxious about mixing them with the radial tires up front. The top end wobble also concerns me, but it sounds like you have been able to manage that. Were the fronts stock size radials or skinnys? My other thought was Nitto 275/60R15s as they might not bite as hard as the M/T. Again, I am just a "Test and Tune" guy, so I don't plan on more than a 2500-3000 RPM launch.

I think both cars are capable of high 12s with wheels and tires.

This is the 2014 GT at home in Florida and at Bradenton Motorsports Park.

Nice looking car. 12's are certainly in the cards for both of your cars with the right weather and traction. I prefer M?T over Nittos.
I have 17x7 Racestars on the front of my car with 215/65/17 radials. Occasionally I use a different front tire but the driving characteristics are the same.

This is my 2012 GT at New England Dragway recently. Barton shifter and two post bracket have made a big difference in getting consistent gear changes even at redline. Still on the stock 235/50R18 all season tires. I was pleasantly surprised that I had some traction, even with the low RPM soft-launch.

235/60R18 A/S tires.

Mine ran 12.9...bone stock engine. Had 20" all seasons too. MT82 w/3.73 rear. Best results were launching right off idle. Mine also had a Barton Rev2 shifter that the original owner had installed.

Love that blue! FAST for a stocker too... congratulations.

You might need even need a trailer, you'd be surprised at what you can fit in these cars if you know how to pack.

That's a full set of 18s (18x9 and 18x10) in the trunk and a complete set of tires on the rear seat. 255/40/18 and 285/35/18.

Not the same platform, but I've been driving my 66 coupe (around 430hp) with drag radials, t5 manual and a 4.11 gear for years with zero issues. I've been caught in the rain and just drove not like a dumbass and was good.

pass1over said:

You might need even need a trailer, you'd be surprised at what you can fit in these cars if you know how to pack.

That's a full set of 18s (18x9 and 18x10) in the trunk and a complete set of tires on the rear seat. 255/40/18 and 285/35/18.

Not the same platform, but I've been driving my 66 coupe (around 430hp) with drag radials, t5 manual and a 4.11 gear for years with zero issues. I've been caught in the rain and just drove not like a dumbass and was good.

View attachment 88344

View attachment 88345

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I'm impressed...haha!!!

diambo4life said:

Mine ran 12.9...bone stock engine. Had 20" all seasons too. MT82 w/3.73 rear. Best results were launching right off idle. Mine also had a Barton Rev2 shifter that the original owner had installed. View attachment 88340

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Check out my time slips from this past Wednesday. The sequence and ET similarity to your slips is amazing. This was my first night with the M/T ET Street SS 275/60R15s. It took me a few runs to adjust, but I am getting a feel for actually having traction at the launch and fighting the bog. Also, because these tires are taller, I am no longer hitting the rev limiter prior to the trap. Given the fact that your times were on street tires, they are certainly more noteworthy.

Good improvement. Just keep playing with it and make adjustments and you should see an even better improvement.

Let me start by saying that I appreciate the responses that I received on this thread. I know that it has been a while since I last posted here, but now that the season is coming to an end at New England Dragway, I wanted to reflect on some of what I have learned. First of all, I certainly had some preconceived notions that proved to be false, as many of you may have already known. Initially, I thought I could limit my launch RPM to 2500 - 3000, but once I had sticky tires on the car, I quickly learned that was not the case. Over the course of 65 runs and adding a 93 octane Steeda tune, I gradually increased my launch RPM to 4300. I am still easing the clutch out, but I finally got my first 1.7x 60 ft this past Sunday and a season best 12.41 ET @ 112 MPH (DA around +450 and temp around 54 degrees). I have attached the three best runs of the day, but I also ran slower times (a pair of 12.66s and a pair of 12.88s). I also learned that shifting up around 7000 - 71000 RPM was not paying off, as the stock clutch tends slow down the gear change. My 12.41 ET was made with shift points around 6800. The only changes that I have made to the car are the Barton short throw shifter, the 275/60R15 Mickey Thompson ET Street S/S tires (changing them at the track, due to the 190-mile round trip), and the 93 octane Steeda tune (SCT x4 tuner). I know that better ETs have been posted for stock 2011-2014 GTs, but I have to say that I didn't expect to get this far. On a separate note, I have started data logging and that is a whole new experience in and of itself. I will say that it has illuminated some things that helped me improve.

Do you power shift or seesaw?

JC SSP said:

Do you power shift or seesaw?

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Seesaw.

This is not me but it’s the way I row gears in my little coupe.


Lol

JC SSP said:

This is not me but it’s the way I row gears in my little coupe.

https://m.facebook.com/jerryzaiden/videos/this-guy-is-a-legend-/1265089050336160/

Lol

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Awesome!! Olympic class rowing!!

Hello Eveyone, I am back in Florida and I have made my first runs of the season with the 2014 GT. My previous best was 13.11 @ 106 MPH, on street tires (2500 DA). I am now running on 285/40R18 Mickey Thompson ET Street S/S tires on 18”x10” Forgestar wheels. The combination is about 22 lbs lighter than the stock wheels and tires (50 lbs each vs. 61 lbs each). I also changed out the factory LCAs with Ford Performance versions, which seemed to be sufficient for the stock level of power. The DA varied from about 1500 - 2000 ft. I did some data logging to try and compare the performance with the 2012 GT and get a baseline before applying a tune. I consider myself fortunate to be able to enjoy this hobby year-round.

Happy Thanksgiving to all!

At the risk of boring people, I will continue to post my experiences with this car. I attended the "Thursday Throwdown" test & tune event this past week at Bradenton Motorsports Park. I was pleasantly surprised to when the newly applied preloaded SCT 93 octane tune and some fantastic air shaved about .4 off the previous best for this car. The DA ranged from +88 to -52 Feet and the temperature ranged from 58 to 56 degrees for the last three/best 3 times (inserted below).

My best time with my 2012 Mustang GT (MT-82 manual, 3.73 axle, Steeda Tune, M/T 275/60R15 ET Street S/S tires) was a 12.41 @ 112 MPH, 1.75 60 ft, 4300 RPM launch. Comparing this to my 2014 Mustang GT (6R80 automatic, 3.15 axle, SCT Tune, M/T 285/40R18 ET Street S/S tires) 12.42 @ 111 MPH, 1.90 60 ft, 1200 RPM launch, it seems that slower 60ft of the 2014 GT is offset by the fact that the automatic only has to shift twice and can accomplish that about .15 seconds faster than I can manually shift three times in the 2012 GT. If you compare the two time slips, you can see the 2012 GT 60 ft lead evaporate as the 2014 GT reduces that difference from the 330 ft mark on.

2012 GT 2014 GT Difference
60 ft 1.75 1.90 .15
330 ft 5.20 5.29 .09
1/8 mi 8.01 8.05 .04
1000ft 10.40 10.42 .02
ET 12.41 12.42 .01