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Bracket Talk Bracket Talk Forum Tech Talk - by Abruzzi Stretching Rear Tires for Roll OutGo | New | Find | Notify | Tools | Reply | |
| Stretching Rear Tires for Roll Out | Login/Join |
| DRR Pro |
Stretching Rear Tires for Roll Out How much in inches have you been able to stretch a rear tire to get the roll outs to within 1/2” of the opposite tire ? Example, if you had them at 102 and 103 -1/4 , have you been able to get 3/4” more circumference out of the small tire and have it maintain that size after racing the first event. What’s the maximum un-matched tire roll out you would accept ?? | ||
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DRR Pro |
I always check roll out and try and make them within a 1/8th “ but a 1/2” will do. I have stretched a tire 1” before to get it within that 1/8th to 1/2”. Have done it to every set of tires I have run. That’s all brands! Brian Mollison 2009 RaceTech Dragster 2020 Sumerduck Dragway VA Top ET Champion 2017 Sumerduck Top ET & SSS Track Champion 2017 MAC Top ET Track Champion 2009 Sumerduck Dragway Va Top ET & IHRA SSS Track Champion 2008 IHRA Division 1 Top ET Bracket Final Runner-up 2007 Colonial Beach Dragway Top ET Track Champion | |||
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DRR Sportsman |
Same here, new hides i always check. Most i have received were within 1/8- 1/2. The set 2 years ago were off 1". Old timer taught me a trick years ago. Take the shortest tire mounted. Put it out in the sun if possible. Basically heat soak. air it up. Told me 15Lbs will start the process. sure enough, got it within 1/4 of the other. Learn something new every day. Sure beats having to send them back I never put any faith in the chalk markings on the tires when new. The set i ordered for the car 1.5 years ago. GY D2A's. i specifically told them 103.5 to 104 if possible. Got them, were marked 104. I measured, came out to 107 1/4. Was fit to be tied.Enough to kill the gear. .This message has been edited. Last edited by: TD3550, | |||
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DRR Top Comp |
I have always stretched them,either to match or get most roll out possible and match at same time. WIth bracket car always try to run the same roll out,its minor change to tune up but it is a change. Nothing too minor in a game where win or loose can be .001 or even less. America home of free. Brought to you by 2nd amendment. | |||
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DRR Pro |
Stretching didn't work for me. Tire would shrink back after 1 race. 1.75" difference is a lot for 28" tires! Best thing I know to do is order measured tires from the distributor that sends a matched pair. Never a problem since I started doing that. It's worth every penny extra. Or...switch to radials. Matt Ward | |||
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| DRR Pro |
Matt, This is exactly what I wanted to hear from someone else. Here's my problem. Last August I had new tires put on and they were 102.5 and 103.75 when mounted (they were marked within 1/2") . That’s 3/4 " too much. I needed to race the next 2 days and the seller / installer said that they'd sterch that much just over-inflate and put in the sun. The sun was going down so that's not an option. If fact, using the sun is a poor option because here in WI we experience much clouds. I pumped the small tire up to 40 psi and left it sit over night. The next day I let air out to 10 psi and had tire to within 1/2" of other. Raced that weekend and checked tire R/O on Monday and its 13/16" more than other tire. I've been repeating this same process prior to racing (and I've had the tire in the Sun on 3 tries) the past 15 events and the same results. The day after racing the tire is 13/16" more in R/O than other tire. Because of this ongoing experiment I can Honestly say that if you have a Hoosier drag slick you cannot stretch it more than 7/16" and "Maintain" that size while racing and after. I just ordered new MT rear tires and I wanted ones that were dated No earlier than 26 week 2017. This is because MT in their 2017 catalog listed there tires as "Newly improved for better air retention". I had MT in 2013 and 2014. They leak like sieves and I slimed one set and dish soaped another. NEVER again. The MT tires show up today with dates of 4116 and 0417. I looked at them and told the dealer to send them back. I'm not taking these. I want fresh stock and the ones that are "Newly improved for better air retention". I told him to order the same 32x14 Hoosier I've been using. BUT, I won't take anything with more than a 3/4" Roll Out difference when mounted. The last set of Hoosiers had a lump in the tread after 50 runs. I agree that rear tires should be made as close as possible to each other in roll out for consistency. Running what I have now I believe can cause more wear and damage to my spool or axles. | |||
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DRR S/Pro |
For what its worth Jason Moulton of MT told me once your better off shrinking the bigger tire to match the smaller tire. Put 1 or 2 lbs of air in the tire and place it in the sun and the nylon will shrink and it worked. He also said after you have done the first burn out on a tire you cannot shrink or stretch the tire from that point on. Your results may vary | |||
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| DRR Sportsman |
In the past I haven't had luck stretching tires - they would stretch for a bit then after running them return to where they started. But I don't think I've ever done it before running them and I've read it needs to be done first. I'll be stretching some today. Bought new MT 3183 from Jegs. Called and ordered and specified that I want a matched set hopefully between 106.5&107. They said they have 15 in stock so that shouldn't be a problem. They came in, one tire is marked 105.25, the other is 105.75. Going to mount and measure them today and stretch if necessary. Will report back. | |||
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DRR Sportsman |
I agree it needs to be done before they are raced on. Ive done it a few times with 32x14's and 28x10's. But only 1/2" or so. | |||
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| DRR Pro |
I think Mr Moulton has great advice …… if you live in Needles, CA. Here in the upper Midwest you have a 2 month window starting next week to attempt following his advice. The dealer is supposed to get my new Hoosiers 32x14 today and I’ll return to have mounted. The plan is to go racing on Fathers day. I’ll post what I end up with if they arrive. | |||
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| DRR S/Pro |
You asked for advice and it was given. Jason said place in the sun, nothing about being 100* out. He also said your better off shrinking the big tire then stretching the little one which I have done and it works. I'm sure the sun comes out for more than 2 months a year where you live. Hope your Hoosiers are what your looking for | |||
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DRR Sportsman |
I've pumped one up to 25psi and left it in the sun to stretch in the past. I find after doing that and running about 1/4-1/2 # more pressure in the smaller tire after a short time all is good. Eric Macchiaroli S/R1355 80 Arrow | |||
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| DRR Pro |
Steve, I value what you had to share and do think it is worth trying. My comment was making reference that it probably would work best at any given time of the year in your neck of the woods as compared to the upper Midwest. But this is what I am going to do. If the RO is within 1/2” after mounting these new tires at 10 psi, I’m going to lower the air pressure to 1.5 lbs in the larger of the two tires and try your method. It just finished raining here today, but tomorrow (Saturday) is supposed to be partly cloudy and 93. | |||
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| DRR Pro |
New 32x14 Hoosiers 18245 arrived at installer this afternoon. Both dated 5-8-18 and 105-1/2 on tread and same mold numbers on sidewall. Rimmed and inflated to 10 psi. On the spin balancer prior to balance he put a tape to them with me standing there. 102 and 102-3/16 . Ready to race father’s day. I’m “Very” satisfied with this, but would have liked to try a 2018 set of the MT 3074S. Perhaps I should contact Dan Fletcher to see who supplies his tires next time ………. | |||
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| DRR Pro |
I raced 1/4 mile for the first time since 2016 this Fathers day and my car has not been this smooth in the past 200+ 1/8 mile runs. I believe much of my vibration problems can be traced back to the last two sets of rear tires. From the set that developed an out of round lump and balancing problems to the last set that could never get closer than 13/16” difference in rollout. I replaced the 4 link rod ends, wishbone rod ends and slide tube, front steering rod ends, steering knuckles, struts and strut towers. The more I replaced , the more violent the shaking felt in the whole car. I hope this stays fixed. | |||
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| DRR Trophy |
I am a MT dealer and I am very knowledgeable on stretching tires. Do not put them in a hot sun as this shrinks opposite of what everybody is saying. I find most dont know process of measuring. First mount tire and inflate to 20 psi and immediately let air to 6psi. Immediately measure tire. Now do second tire. You cannot leave air pressure high and come back later to measure. Had a customer call me and said tires were 102 and 104 and was screaming. Turns out they both when air and checked correctly they were both 1051/4. | |||
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| DRR Trophy |
Also sell Hoosier and the same thing happens with them. Hoosier customers say they never had mis matched tires only because they never checked. Sizing is a problem with all brands of slicks. Nature of the business. A dealer that has a post inflate is the way to go but racers don't want to pay for someones labor for a perfect match. I know because I used to post inflate slicks. Did not sell many sets. We have to do just like Jegs or summit does to be competitive. Sad. | |||
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| DRR Trophy |
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| DRR S/Pro |
Pretty much backs up what Jason Moulton at MT told me, your better off shrinking the bigger tire, that the nylon in the tire shrinks | |||
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| DRR Pro |
I’m taking notes on what you have posted and have a question. What does the initial 20 psi inflation do? Is this for seating the tire bead to the rim or some sort of normalizing? I wish you were in my area as I’d be happy to purchase from you and pay a reasonable fee to have you guarantee the tires you sell me are within 1/2” or less of my 10.5 psi racing setting when installed, balanced and delivered by you. I still stand by my original comment to Steve. The Sun ain’t shining yesterday, today, tonight or tomorrow (this is true in 53056 right now). What do I do with this mismatched rollout set of tires to get to within 1/2” of each other? My recent tires were inflated to 10psi and then checked on the balancer for roll out prior to the second tire being mounted. They were within 3/16” of each other. After I installed on the car and checked the next morning while still on the lift, they had grown an additional 1” to 103 and 103 -3/16 @ 10 psi overnight. I tow an enclosed trailer and keep the tires out of the sun when I got to the track. Aired to 10.5 psi and made 5 quarter mile runs. They worked great. The next day they checked 103- 1/2 and 103- 5/8 @ 10 psi. Hoosier advertises these tires as 102” RO. | |||
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Bracket Talk Bracket Talk Forum Tech Talk - by Abruzzi Stretching Rear Tires for Roll Out
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