Which Pair of my DRs for the best ET?

[SpeedRacerX]

Weather is cooling down and I'll be headed to Atco soon to finally get in the 11's now that I figured out my boost issue.

I have two pair of Mickey Thompson ET Street SS drag radials to choose from.

My older 255/60-15 on stock wheels or...
My newer 295/55-15 on 15x10 gbody aluminum GN wheels. This choice was for looks by the way.

I'm not so much concerned about the weight. I'm concerned about the diameter.

The 255 is shorter by about 1".
I should run a quicker ET with the shorter tire, right, at my power level??

Car has previously gone 12.2@112 with 1.65 60 foot on 22# boost with alky.

Thanks in advance for the advice.

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[The Granny]

in theory you should be able to run faster with a smaller tire, assuming you can hook with either tire. bring both wheel sets and try them back to back!


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[Royal-T-Ltd]

Actually I thought with taller tires you get more MPH, as long as the car has enough power. I'm sure someone will verify, I know I'm switching to a slightly taller tire very soon. Either 27" or 28"


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[gusszgs]

JMO
But if the motor is stock internally, I think a 28" will serve you better. The taller tire will put the motor in a happier power band.

 

[BobbyBuick]

if your car is stock i would stay closer to 27 inch or.255 .the ss tires are not as good as the 275 pro and bracket pro .those 2 tires are the best MT makes the et streets an ss tires break loose on my car and the bracket pros and 275 pros hold to mid to high 1.30 60 fts

 

[Thumper]

In TSA I found my combo liked the shorter tires, this was with a lock up vigilante converter locked at 95 mph, 26 " 275/50/15 did good but the 27" 255/60/15 did the best.

Now I'm running a 28" 275/60/15 with a non lock up to try keeping rpm down as my non lock is 300 rpm higher going thru the traps.

In my testing the shorter allowed rpm and boost to ramp up quicker, the taller helped rpm in the end of the track. Approximately 200 rpm change for each 1" of height if I remember correctly.

Of course this is what I found on my tune, others may very a little.

 

[blklt1z28]

295's

Keeping the rpm's down at the top track will help you et better since you still have stock heads/cam. These motors make torque, and they don't make a lot of hp up top. These things are usually all in around 4800rpm. Use the torque to et, not the hp.

When your combo changes then make adjustments...but once you go to a 28" tire you usually never go back.

 

[SpeedRacerX]

I guess I should have listed my mods in case you can't see from a cell phone.

Stock gear with Eaton posi, fresh valve springs, TA49, 3" downpipe, dump, exhaust, 42# injectors, alky, alky chip, adjustable fuel pressure, CAS V4S intercooler, big mouth intake, misc freshened or supporting stuff.

Stock trans and converter for now.

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[SpeedRacerX]

Also, how far can I push the boost just for a few runs at the track with alky? 25#, 26#?

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[Royal-T-Ltd]

Also, how far can I push the boost just for a few runs at the track with alky? 25#, 26#?

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Every car is different and your tune may be different, so i don't want to spit an arbitrary number out... With that being said - i run 25-26. [maybe more, have to hook my new SSI Transducer up] but i have a FMIC as well as ALKY.

HTH
aaron

 

[Mr.Spool]

I guess I should have listed my mods in case you can't see from a cell phone.

Stock gear with Eaton posi, fresh valve springs, TA49, 3" downpipe, dump, exhaust, 42# injectors, alky, alky chip, adjustable fuel pressure, CAS V4S intercooler, big mouth intake, misc freshened or supporting stuff.

Stock trans and converter for now.

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The 295/55/15 will be the faster tire with the 49 turbo,provided you plan on hitting it with boost and rpm off the line.that the tire I used with a 49 turbo/stockish motor combo that went 10s with a 1.4 60ft.rollout and sidewall are the key if your combo hits fast and hard like a 49 should.

 

[Mr.Spool]

Also, how far can I push the boost just for a few runs at the track with alky? 25#, 26#?

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You can run repeated passes with a richer Afr.your stock trans will not.

 

[SpeedRacerX]

You can run repeated passes with a richer Afr.your stock trans will not.

Yes, the trans is on borrowed time, although knock on wood, I have no issues yet. I plan to address the trans in the spring.

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[SCOOBY DOO]

Bump the boost to 25 and it won't matter.

 

[DoubleD]

Take both, the buick has a big trunk!