Noticed my 275-60/15 MT Dr's seem to all of a sudden seemed to have gotten a squared off shoulder so the actual contact patch is wider. They've got about 500 street miles on them now (figure 80-90 miles round trip to the track, depending on what track I go to) and maybe 20 passes. These had a noticeable round shoulder that has just went to being squared off. I run them at 25-28 PSI on the street and 14-16 PSI at the track. Is this normal for these?
Drag Radial Break-In??
GRN69CHV
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Noticed my 275-60/15 MT Dr's seem to all of a sudden seemed to have gotten a squared off shoulder so the actual contact patch is wider. They've got about 500 street miles on them now (figure 80-90 miles round trip to the track, depending on what track I go to) and maybe 20 passes. These had a noticeable round shoulder that has just went to being squared off. I run them at 25-28 PSI on the street and 14-16 PSI at the track. Is this normal for these?
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thats how mine are with about 3-4k miles on it. lately i've been running the 40-44psi in them thats recommended. i should air them down though.
aaron
aaron
Don't know how, I can see the air through mine way before 1K miles. I usually run 25 psi on the street and 16.5 at the track. Every trip to the track means a 13 mile trek back home with only 16.5, but they're pumped back up to 25 before hitting the road again.
Fortunately, most DR's have as many miles left in them after the grooves disappear as they did while they were still evident. Once the cords start showing, then it's time to start thinking about new shoes. At least that's my strategy, plenty of TCer's can vouch on that one. I think that Daryl (Daryl Yost) is the only TCer to ever see a groove on one of my rear tires and that's only because he was pitted next to me at ALL OUT Vegas when a new set was delivered to me at the track.
Experimenting with MT's, BFG's and Hoosier's, all have continued to work at the track equally as long. In fact, the BFG's were better after all signs of tread pattern ceased to exist.
Sorry about that. I had even walked outside to check, but forgot to include my findings.
I have a pair of each:
275/50-15 Hoosiers with 50% groove left. Yes, the contact patch appears wider, side less curved than new.
275/60-15 MT Street Radials, no center groove left. Patch wider, less shoulder curve than when new.
325/50-15 MT Street Radials, one 5%, other 25%, sidewalls appear curved, similar to new.
These are all on 15" X 8" Weld Wheels. The 325's probably show less tendency to flatten out because rim width. They really should be on 10" wide wheels and, if so, would likely wear like the others.
Can't say that I noticed it before though.
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5,710 Posts
my sidewalls are still kind of rounded. but the treat width is pretty flat.
im down to about 2/32 on the center and 5/32ish on the outside treads.
mine hold consistent air pressure, but that might be because i drove the car somewhere close to 100miles a day.
aaron
im down to about 2/32 on the center and 5/32ish on the outside treads.
mine hold consistent air pressure, but that might be because i drove the car somewhere close to 100miles a day.
aaron
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5,710 Posts
im actually running the 275/50's on an 8" wheel.
i was able to get a 1.96 60 from them, but it took a big burnout. still need a bigger burnout and bigger balls to get a lower 60.
i was also on 40-44psi of air that night too.
aaron
i was able to get a 1.96 60 from them, but it took a big burnout. still need a bigger burnout and bigger balls to get a lower 60.
i was also on 40-44psi of air that night too.
aaron
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5,710 Posts
1st gear burnout i did for some reason, for about 4-5 sec. so i didnt get enough tire spin, and too much air pressure i know.
but i went 13.07 at 104 with 1.96 60 on complete street trim.
aaron
I found that MT, BFG and Hoosier DR's work best on my car with 16.5psi, regardless of the various sizes listed above. Agree on limiting the burnout too. Start 'em spinning slow until it shifts into third, then wind it up and let it roll out. Only at max rpm for a second or two. Unless, of course, you want the side of your house to look like mine.... A virtual DR graveyard.
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i will just do a 2nd gear 5k burnout for about 3-4 sec since i have a stick car.
i tried a 2-3 sec one with the higher pressure and it didnt hook. but my pressure is the reason for my traction issues.
aaron
i tried a 2-3 sec one with the higher pressure and it didnt hook. but my pressure is the reason for my traction issues.
aaron
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11,823 Posts
Aaron
I started out with the MT drag radial and a 4 speed. Come to find out that tire does not really like stick cars, but you probably can be OK.
I switched to the MT ET Streets and reduced my 60's from 1.8 to 1.6.
No change in launch.
I found out that a second gear burn out is the best with a short burn out.
Unless you have a true all out slick a huge burn out is not necessary.
I also found that my ET Streets want as much air as possible without blowing the tires off. For me that is right around 19 lbs.
I started out with the MT drag radial and a 4 speed. Come to find out that tire does not really like stick cars, but you probably can be OK.
I switched to the MT ET Streets and reduced my 60's from 1.8 to 1.6.
No change in launch.
I found out that a second gear burn out is the best with a short burn out.
Unless you have a true all out slick a huge burn out is not necessary.
I also found that my ET Streets want as much air as possible without blowing the tires off. For me that is right around 19 lbs.
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