I picked up today at Summit racing in Akron a new set of Hoosier 25-5-15 front drag tires . I did not notice till I got home that roll out is marked on tires from Hoosier , 1 at 77-1/2 , other at 78-1/2 , 1" variance ? I am well aware of importance on roll out on rear slicks , but was un aware that front tires would vary . This is my first set of front Hoosier , always ran goodyears than Phoenix of late . These will go on a super gas car . I have emailed Hoosier for there recommendation ,what have you guys experienced with drag front tires and there matching or varying roll outs ? How much variance to affect steering ?
Wait for it! Wait for it!
You will hear from the divine source on this soon enough.
I'm sure it would have a significant difference on how the car sets up, preload would be dramatically affected with the 1/3 of an inch diameter change. If the car was set up to no difference in size... if you set the car up with those tires then swapped them side to side it would be 2/3 inch ride hight change. That would be huge. Id send them back. Not because they are Hoosier, but because that would be a pain in the ass to set up a car with.
4.36 @ 159 so far.....
6.86 @ 198 trying for more......
533" single carb
235" Harrison 4-link
Send them back...
Did you measure the tires you took off to see if they were equal ?
Another thing, check the runout on those tires. I had a set of the same size that would rub the struts, turn the same tire around on the rim and it would not rub! I had a lengthy discussion about it with Hoosier tech, not sure if they fixed the mold or not.
Thanks to all who has responded , I will return to Summit and see if they have a identical pair or try another brand or put MT ET front back on .I have not dis mounted my old ones yet , so I will measure them to see what the roll out is on them . They ar MT ET fronts 24-4.5-15 , they came on car when I purchased last year , date code shows over 10 years old. I was trying to gain a 1" height increase , raising nose of car . That is why I looked at Hoosier specs , tire is narrower than MT but taller and I have to be careful not to rub fender . Do all brand front drag tires come with roll out marked ? What brands have you guys have had good success with ?
I don't think there is a track surface we race at that is within 1/3 of an inch.... Also, radius would affect pre-load not diameter so your talking .150" different. Last, I bet if you mounted the tires and measured them now, they would be way closer to the same. I don't think the checking process is automated meaning if the 78.5 tire was blown up and measured just as soon as it left the mold and the 77.5 tire had some amount of waiting period before checking I suppose you could get skewed numbers...?
But, at the end of the day its your hard earned money so send them back and get perfect...!
(All of that for that...?!)
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and so would I. Those numbers marked on the tire are out of the mold.
You will get a matched pair from the Hoosier distributor.
I have received a prompt reply from Hooosier Rep this morning , he advised to return and get matched set . I checked the MT ET front drag tires that are on car now as some one requested on here , they are 1/2" difference between them . I have always been aware of importance on rear slicks , but front tires ? Apparently Hoosier are only ones measuring an marking roll out at the time of manufacturing ? Summit seems to be un aware of them being marked or the importance of matching properly . I am going to check with a reputable drag racing tire retailer to see what they have to say about it , I will keep you guys updated
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I've never purchased my slicks nor front runners from either summit or jegs for the fact you get what they grab, regardless of rollout or manufacturer dates.
If you want front tires that are actually 25” tall when mounted I suggest that you get ones marked 78.5. The 77.5 will be at 24.6”. My 25- 5- 15 Hoosier fronts were both marked 76 5/8 and they are only 24.375” tall.
My last set of rears were marked within 1/2” of each other. After they were rimed the difference in RO was 1.25” between the two. All these tires were directly from a Hoosier tire Distributor.
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