Front tire size versus reaction time

7423 · 05-31-2010, 06:10 PM

Currently running 27.5 Mickeys and need to pick up my lamp a couple three hundreds. Thinking about a pair of 25's or 26's. Any thoughts on what that change will net me?

partsbob67 · 05-31-2010, 08:53 PM

they make the car faster.... less money in the wallet= less weight!!!!

Michael Beard · 06-03-2010, 10:16 AM

2" diameter will get you roughly .015.

I wrote a rather long editorial for ThisIsBracketRacing.com that covers that and numerous other ways to change your R/T's.

7423 · 06-03-2010, 11:38 AM

Quote:

Originally Posted by Michael Beard

2" diameter will get you roughly .015.

I wrote a rather long editorial for ThisIsBracketRacing.com that covers that and numerous other ways to change your R/T's.

Thanks for the reply Michael, do you have the link for that editorial?

Michael Beard · 06-03-2010, 06:01 PM

I do, but it is a 'pay' subscription site. You have to be a member to read the site's content. It's WELL worth it, though! The other info on the site has helped me win a bunch of specific important rounds this year.

My editorial is at: http://www.thisisbracketracing.com/g...s=58530B010301

Tim Kish · 06-04-2010, 08:07 AM

I'm sure Michaels editorial covers it but one key consideration is if your car goes forward or straight up. If you are jerking the tires up outta the beams, diameter isn't going to help.

Adger Smith · 06-04-2010, 12:30 PM

Sometimes a tire that is quite a bit shorter will change the weight bias/suspension set up of the car so much it will make the car leave slower. To do a valid comaparison of RT/tire height you have to maintain the ride height on the car the same, or as close as possible, for both tests.

sprnova · 06-04-2010, 02:10 PM

I tried the same thing thinking mt RT would be better for a pro light. I was wrong. It actually made it worse and the car slowed down. I think it was because it made the motor pick up the front end from further down then normal. As someone already said. It changes the ride height. As for making the car faster, wouldnt it slow it down by putting a small tire? Less run out = slow ET More roll out = a quicker et. ( more of a run at it)

Adger Smith · 06-04-2010, 04:05 PM

I think you assumptions on your car are correct. "If" the car leaves the same... Back to ride height... the shorter roll out tire should make the reaction time quicker. It will also decrease the ET a little due to the reduced rollout... Think of Roll Out as a distance where you gather FREE speed before breaking the beams. How much free speed you get depends on many variables... Rear tire/suspension/converter hit/and just how hard your combination leaves all play roles in RT and ET's. That is why some say .005 and others say .015 with different tire sizes. Some other component of your suspension/weight bias or even tire slippage/hit changed when you put on the smaller tires.

05-31-2010, 06:10 PM	#1
7423 Senior Member Join Date: Dec 2006 Posts: 639 Likes: 0 Liked 1 Time in 1 Post	Front tire size versus reaction time Currently running 27.5 Mickeys and need to pick up my lamp a couple three hundreds. Thinking about a pair of 25's or 26's. Any thoughts on what that change will net me?

05-31-2010, 08:53 PM	#2
partsbob67 Member Join Date: Apr 2005 Location: rohnert park,ca Posts: 414 Likes: 11 Liked 78 Times in 11 Posts	Re: Front tire size versus reaction time they make the car faster.... less money in the wallet= less weight!!!! __________________ bob beals 7244

06-03-2010, 10:16 AM	#3
Michael Beard VIP Member Join Date: Sep 2002 Location: Columbus, OH Posts: 4,060 Likes: 0 Liked 13 Times in 9 Posts	Re: Front tire size versus reaction time 2" diameter will get you roughly .015. I wrote a rather long editorial for ThisIsBracketRacing.com that covers that and numerous other ways to change your R/T's. __________________ Michael Beard - NHRA/IHRA 3216 S/SS

06-03-2010, 06:01 PM	#5
Michael Beard VIP Member Join Date: Sep 2002 Location: Columbus, OH Posts: 4,060 Likes: 0 Liked 13 Times in 9 Posts	Re: Front tire size versus reaction time I do, but it is a 'pay' subscription site. You have to be a member to read the site's content. It's WELL worth it, though! The other info on the site has helped me win a bunch of specific important rounds this year. My editorial is at: http://www.thisisbracketracing.com/g...s=58530B010301 __________________ Michael Beard - NHRA/IHRA 3216 S/SS

06-04-2010, 08:07 AM	#6
Tim Kish Member Join Date: Nov 2003 Location: Kalamazoo, MI Posts: 281 Likes: 2 Liked 11 Times in 4 Posts	Re: Front tire size versus reaction time I'm sure Michaels editorial covers it but one key consideration is if your car goes forward or straight up. If you are jerking the tires up outta the beams, diameter isn't going to help. __________________ Tim Kish 3032 SS/GS

06-04-2010, 12:30 PM	#7
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,446 Likes: 575 Liked 880 Times in 311 Posts	Re: Front tire size versus reaction time Sometimes a tire that is quite a bit shorter will change the weight bias/suspension set up of the car so much it will make the car leave slower. To do a valid comaparison of RT/tire height you have to maintain the ride height on the car the same, or as close as possible, for both tests. __________________ Adger Smith (Former SS)

06-04-2010, 02:10 PM	#8
sprnova Junior Member Join Date: Oct 2009 Location: Glendale, AZ Posts: 53 Likes: 0 Liked 0 Times in 0 Posts	Re: Front tire size versus reaction time I tried the same thing thinking mt RT would be better for a pro light. I was wrong. It actually made it worse and the car slowed down. I think it was because it made the motor pick up the front end from further down then normal. As someone already said. It changes the ride height. As for making the car faster, wouldnt it slow it down by putting a small tire? Less run out = slow ET More roll out = a quicker et. ( more of a run at it)

06-04-2010, 04:05 PM	#9
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,446 Likes: 575 Liked 880 Times in 311 Posts	Re: Front tire size versus reaction time I think you assumptions on your car are correct. "If" the car leaves the same... Back to ride height... the shorter roll out tire should make the reaction time quicker. It will also decrease the ET a little due to the reduced rollout... Think of Roll Out as a distance where you gather FREE speed before breaking the beams. How much free speed you get depends on many variables... Rear tire/suspension/converter hit/and just how hard your combination leaves all play roles in RT and ET's. That is why some say .005 and others say .015 with different tire sizes. Some other component of your suspension/weight bias or even tire slippage/hit changed when you put on the smaller tires. __________________ Adger Smith (Former SS)