Going with 28X10.5X15 ET Drags
02-28-2008, 07:40 PM
#1
Going with 28X10.5X15 ET Drags Here is what I can do. I can move the rearend forward to allow 5/8 of an inch in front of the tire and behind the tire!
Car is a 98 Formula no problem with top of tire. Here is the question is 5/8 of an inch enough in front and behind the slick for tire growth? Without adjusting anyting the back of the tire just barley touched the bumper cover in the 1/8 mile at 99 MPH's. How much more will the tire grow in the 1/4? It will run 123 MPH's in the 1/4!
Running a 26X10X15 ET Drag and also ran a 26X11.5X15 ET Street with no problems.
Car is a 98 Formula no problem with top of tire. Here is the question is 5/8 of an inch enough in front and behind the slick for tire growth? Without adjusting anyting the back of the tire just barley touched the bumper cover in the 1/8 mile at 99 MPH's. How much more will the tire grow in the 1/4? It will run 123 MPH's in the 1/4!
Running a 26X10X15 ET Drag and also ran a 26X11.5X15 ET Street with no problems.
02-28-2008, 08:55 PM
#2
02-28-2008, 09:09 PM
#3
I personally don't think that's enough.. I'd trim the inner lip off the bumper cover to get as much room there as you can, and the lower inner part of a firebird has a triangular section of metal, I cut that out and filled the hole with some body sealer, you can't really see it, and now it's coated in rubber anyway LOL. But, it got me about an inch all the way around the tire, and at 139 they don't hit at all, I don't think they will ever to be honest.
03-01-2008, 06:57 AM
#5
These tend to grow alot more on the top end from what I understand. Get at least 3/4 of an inch and you should be good.
To be safe though, angle your mirror's so you can see the wheel well's the first full run, so if you see any smoke you can get out of it before you cut down a tire. DO a good burnout, and have someone check after you pull out of the burnout box to make sure they didn't rub doing that, if they rub there, then you're gonna have a problem.
To be safe though, angle your mirror's so you can see the wheel well's the first full run, so if you see any smoke you can get out of it before you cut down a tire. DO a good burnout, and have someone check after you pull out of the burnout box to make sure they didn't rub doing that, if they rub there, then you're gonna have a problem.
03-01-2008, 08:12 AM
#7
My dad is running that same tire and had 3/4 of an inch front and back.When on the dyno it rubbed,tire grew 2 inches in total height,so 1 inch on each side.He thought he had plenty of clearance,but it was not enough.This is on a 2000 formula.28 x 10.5 et drags.He runs 125 mph in the 1/4
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03-01-2008, 10:20 AM
#8
Wow that is a lot of growth! I may have to re-think this a little more. When I go across the finish line my shift light is just starting to flash at 6400 RPM and I have the limiter set at 7200 RPM and actually shift at 6900 from 2nd to 3rd on a NA run and the car will run 10.75 to 10.80 depending on track and weather at 123 MPH.
If I go with the 100 HP shot of dry NOS the most I have ever used was 75 HP but that was on the old engine combo how much is that going to change my RPM's. I have a 4.10 gear with the 26X10X15 ET Drag now.
I wonder if the car would pull through on the top end with the 26 inch tire if I shift at say 6600 from 2nd to 3rd and let the NOS dig the car out of the lower shift point?
I really don't wont to worry about cutting a tire at 123 MPH!!!
If I go with the 100 HP shot of dry NOS the most I have ever used was 75 HP but that was on the old engine combo how much is that going to change my RPM's. I have a 4.10 gear with the 26X10X15 ET Drag now.
I wonder if the car would pull through on the top end with the 26 inch tire if I shift at say 6600 from 2nd to 3rd and let the NOS dig the car out of the lower shift point?
I really don't wont to worry about cutting a tire at 123 MPH!!!
03-01-2008, 10:23 AM
#9
Great thread subject. I just bought some 28x11.5x15 M/T slicks. Ok, my ? is how did you move the rear forward 5/8 inch? Did you do it by adjusting the LCA'S? Is it actually better to just trim-up the room for them? It looks like I'll have to do something here with these tires on.
03-01-2008, 10:39 AM
#10
In my case I will adjust the LCA and TQ Arm and may even have to adjust the Panhard bar just a litte to make sure everything is square. That is why I wanted to ask the questions I have.
It seems like a lot of work when the 26 inch tires are giving me 1.40 60 foots NA. I just don't won't to run out of gear in the 1/4!!
I guess I could just let off the button if that happens. But man that is hard to do on a good run!!!!
It seems like a lot of work when the 26 inch tires are giving me 1.40 60 foots NA. I just don't won't to run out of gear in the 1/4!!
I guess I could just let off the button if that happens. But man that is hard to do on a good run!!!!
03-01-2008, 10:58 AM
#11
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I have almost exactly 5/8'' on each side of my 28x11.5 et drags, and I trap around 124 and I was having rubbing issues at the end of the track. Not real bad but it was def. rubbing. I plan on taking a little more off my fender and bumper cover, before this season.
03-01-2008, 04:48 PM
#13
You are kidding right? I am not going to put my car on 4 jack stands and put it in gear and run it up to 123 MPH and 6500 RPM that would be insane. I don't even like the way a dyno feels!! Plus they would have me in jail! LOL.
I will just stay with the 26 inch tires until I have traction issues. If I have to take my finger off the button before the finish line that is what I will do!
I will just stay with the 26 inch tires until I have traction issues. If I have to take my finger off the button before the finish line that is what I will do!
03-01-2008, 05:07 PM
#14
I dunno, I have about 7/8 of ain anch and went 139.2 in the 1/4 (video in my sig) and it didn't run at all. These are the M/T 28x10.5x15S tires though, S standing for stiff sidewall. THey may grow a little less because the sidewall's are stiffer, but I doubt it made that much of a differnece.
You can get the tire in there, and it will work, just take your time and trim a little where it's needed, and you will be o.k. The traction and consistancy have proven to be well worth the work.
You can get the tire in there, and it will work, just take your time and trim a little where it's needed, and you will be o.k. The traction and consistancy have proven to be well worth the work.
03-01-2008, 06:19 PM
#15
I went back and looked at my original post. Right now the way the rear end is set up I have 2 inch in the front and 1 3/8 at the back of the tire with the 26 inch tire on there. So I can move the rearend forward and get a little over 5/8 an inch in front and back of the 28 inch tire!
I am looking at what I will need to trim now to see if I can get more. I know it is worth the effort I just don't want to take a chance on cutting a tire down.
I am looking at what I will need to trim now to see if I can get more. I know it is worth the effort I just don't want to take a chance on cutting a tire down.
03-01-2008, 07:25 PM
#16
Try to borrow a set of tires the size you need on the same width rims and do like RagenZ28 said.Put it on jack stands and bring it up to speed with someone watching the tire growth.Just block the front tires up,the car is not going to go anywhere with the rear off the ground.