[DEANGEL]

I was prepping the car for drag racing tomorrow and noticed these diagonal lines on the sidewalls of both rear tires. The diagonal lines are all the way around both tires. They are Mickey Thompson 305/45-17 ET Street R Radials on Forgestar single beadlocks. I run them at 20-21 psi at the track and 30 psi when driving to the track.

I also noticed that they have spun on the rim about 4" on driver side and 2" on passenger side. I have kept the beadlock bolts at 144 in/lbs (12 ft/lbs).

My 60' times are typically high 1.5's to low 1.6's.

Any thoughts on if this is normal and any reason for concern?

 

[drive_55_not]

> they have spun on the rim about 4" on driver side and 2" on passenger side <<

That is why the sidewalls are twisted. I'd break em' down and re-seat em.

I have the same tire on a Race Star wheel and I'm really regretting getting them, I never had any issues with my 275 M&H DR slipping on the Race Star. The ET R's slip a couple inches after just a handful of launches, makes it impossible to keep them balanced and those things will shake the rear apart when they go out of balance.

.

 

[moparjim]

Is it possible that the tire is twisted from slipping on the inside. You mentioned they have moved so is this on the inside that you see that? Or is it slipping on the outside? If you see that movement on the outside I would bet the tire is twisted. That's what the sidewall looks like to me.
I mount my tires dry and last season my right one went all the way around. I have been trying to figure out why I get random vibrations. Sometimes it shakes the car.
With my RaceStars on this happened and now with the Forgestar it hasn't. I'm wondering if my inside slipped more or less than the outside twisting the tire.

 

[DEANGEL]

Thank you for the replies. I know they've twisted on the outside where the beadlock is. I took a picture of the tire sidewall and valve stem location when they were new and now they have slipped 4" and 2" on the outside. I don't know how much they slipped on the inside.

 

[DEANGEL]

I was wondering if the tires are folding down on my launch causing the diagonal lines. I don't have anyone with me to watch or take video of my racing to show what's happening during the launch.

 

[moparjim]

I was wondering if the tires are folding down on my launch causing the diagonal lines. I don't have anyone with me to watch or take video of my racing to show what's happening during the launch.

Probably not the case as you mentioned you have them set at 21. I just looked for a pic and found a video but it was dark. I had to lighten the pic/screenshot to see that mine don't wrinkle or anything at all on the hit.
At least not from that pic. Mine are set at 21 cold so higher than that at launch from the burnout. I don't do a very aggressive burnout.
So with all that info the lines are probably from the tire being twisted. How bad it's twisted is the question.

 

[sc4.6]

My ET Street R's have the same lines. I always thought it was due to the the sidewall wrinkling on launch because they do it every time my car hooks. Now I'm wondering if it's a combination of the sidewall wrinkling on launch and the tire twisting, good chance this is the case. I'm going to re-seat my tires before race season starts and mark them to see if the tires are in fact twisting.

 

[moparjim]

That looks like a good reason for those lines.
Unfortunately I don't have a good picture except from an overcast day at a distance.
I had to take a screenshot then zoom in and brighten the pic. So who knows how good it is.

 

[DEANGEL]

My ET Street R's have the same lines. I always thought it was due to the the sidewall wrinkling on launch because they do it every time my car hooks. Now I'm wondering if it's a combination of the sidewall wrinkling on launch and the tire twisting, good chance this is the case. I'm going to re-seat my tires before race season starts and mark them to see if the tires are in fact twisting.

Thank you for posting that picture. That's exactly what I imagine my tires doing at launch. That is the exact slant of the lines on my sidewalls. I'm thinking I need to try a little more tire pressure.

 

[sc4.6]

Thank you for posting that picture. That's exactly what I imagine my tires doing at launch. That is the exact slant of the lines on my sidewalls. I'm thinking I need to try a little more tire pressure.

Now that I think about it, I had the tires in my pic on a set of non-beadlock wheels before getting beadlocks and I didn't have the lines, they only appeared after switching to beadlocks. I switched to beadlocks because the tires were slipping on the non-beadlock wheels.

I wouldn't worry too much about the lines, my tires are basically due for replacement and I haven't had any issues with them. But curiosity has got the best of me, so I'm going to re-seat the tires and mark both sides to see if the inside is slipping and causing the tires to twist.

 

[sc4.6]

That looks like a good reason for those lines.
Unfortunately I don't have a good picture except from an overcast day at a distance.
I had to take a screenshot then zoom in and brighten the pic. So who knows how good it is. View attachment 615352

It doesn't look like there is any sidewall wrinkle in that picture. You are probably getting enough tire slip on the wheel to prevent wrinkling, that is also what I was experiencing before I went to beadlocks.

 

[DEANGEL]

Same here with my tires being about ready for replacement. I'll also mark the inside of the wheel & tire so I will know if they are slipping.

 

[baabootoo]

Anyone asked Mickey Thompson yet? I'm awaiting an ET Street R, in 18", due to an imbalance issue.

 

[WickedHEMI]

Better to call the manufacturer than to speculate