Cons to going to 26" tire?

[one eyed willy]

Turbo, 3.55's.TR6060 from a 07-08 Shelby with stock gearing. Approx 3800 lb with me in it.

First time at the strip in 2 years, "street heat" which I'm guessing means all the ricers are trying to run 14's.Currently on 28" MT ET Streets I'm at the top of third with my shift light on soon as I hit the 1/4. With 9# of boost I'm trapping about 116mph with very crappy track prep, 2.1 60ft. (In the past I usually hit 1.5 60 ft).


In the past I've always seemed to run great on 26" tires, and I'm guessing with my gearing, 28" is just too tall?

 

[skwerl]

I had the same issue with 3.73 gears. Always ran great with 26" tires until the very end when I was getting close to running out of 4th gear at 136-137mph. I can't figure out why 28" tires are so popular.

 

[JoshK]

I was running a little taller(305/45-18) when I went to the track. I have 4.10s with my 6060 and was crossing the line at about 6000 rpm in 4th(trapped 135). With my rear gear the 28 works well and that is how I set it up. with your 3.55s, a 26" tire will probably work better.

 

[JeremyH]

I currently don't shift into 4th. I trap 124-126mph in 3rd gear at 6800-6900rpms. 6060 3.55 gears 28" tall tire. Shift at 6900 on the 1-2 and 2-3 shift.

When I rebuild the rear end I'm putting 3.90s or 4.10s in and dropping my shift points down to 6500ish. I like the 28" tire for more squat and contact patch with manual trans.

 

[JoshK]

Here is a screenshot of the spreadsheet I used for selecting gear. The first two charts show what your car would be with a 26" tire vs a 28". The third is with 4.10s and a 28" tire.

 

[JoshK]

so the airlift definetly hurt your 60' times one eyed willy?

 

[one eyed willy]

so the airlift definetly hurt your 60' times one eyed willy?

Don't know yet, need to get it on a good prepped day. I used to be able to launch on the WOTBOX set to 4k RPM, 6-7#'s of boost, no problem. On this particular night I couldn't leave on anything much over idle without blowing the tires off.

Ricers running through the water boxes, burning out with their street tires and diesel trucks blowing their shit all over the track,lol. I'm hoping it's not the air lift.....if so then I'll have to change out the rear bags when I go to the track.

How good are ET streets suppose to be? Seems my old 26" tires were MT but I don't think they were ET streets.

 

[GI Joe]

28" need 410 gears. 26 like 373..There are exceptions.
Why do people like 28" beside the "filling the wheel well?"...The real answer is footprint provided by roll out. At about 700 hp it becomes very helpful.
When the tire flattens on launch, a larger diameter tire will create a larger flat footprint and increase initial bite. If everything else is adjusted right this will result in improved 60 ft times and increased mph as the tire grows.
You can go too big however....

 

[psfracer]

Yep and it depends on your power level also. I like 29.5s with 4.10s but I also have around 1150 hp.

When I had 604 rwhp with the whipple, I ran a 28 tall M&H with 4.10s, and hit the traps anywhere from 132 to 134 mph depending on the run with the 4R70W, with the converter in lockup.

Just depends on the combo and how much HP you have and where you want the rpm at the end of the run.

 

[psfracer]

Turbo, 3.55's.TR6060 from a 07-08 Shelby with stock gearing. Approx 3800 lb with me in it.

First time at the strip in 2 years, "street heat" which I'm guessing means all the ricers are trying to run 14's.Currently on 28" MT ET Streets I'm at the top of third with my shift light on soon as I hit the 1/4. With 9# of boost I'm trapping about 116mph with very crappy track prep, 2.1 60ft. (In the past I usually hit 1.5 60 ft).


In the past I've always seemed to run great on 26" tires, and I'm guessing with my gearing, 28" is just too tall?

Here is the thing. As of right now, maybe you would benefit from a 26 tire. But that will change as soon as you go to 16 psi boost. And at that boost level I thought turbo cars liked being loaded that way anyway. But, trapping 116 mph right now, the 26 will probably be better for you.

But if you look at the "list", the 28 tall tire in conjunction with a 4.10 gear seems to be the most popular. Of course, depending on the trans you run and what kind of F/I you have could change your choice.

One last bit of info: A couple years ago, a friend of mine had a 5.0 with a kenne bell with an auto. He went from 3.15s to 3.73. No difference in ET, but the car was making close to 800 rwhp.

 

[one eyed willy]

If the track was hooking for shit I would have bumped it up to 16psi, with the condition of the track it just didn't feel safe....hopefully I can hit it soon and get some traction, then I'll try it out on higher boost before changing it up.

 

[psfracer]

^^^ thats exactly what I would do. Run it first at the boost level you think you will end up at before making other changes.