What size tire do i run?!?!? please help

[famousfamily32]

Here's the deal. I have a 99 GT with basic bolt ons, tuned, aluminum drive shaft, 4.10 gears, lowered drag launch suspension. Right now i have skinnies up front with a 15x8 inch summit star with 4.5 backspacing. The tire i have on now is a gforce drag radial 275/50/15. There is plenty of room and the tire sits even with the fender. but it rubs a little bit on the outside of the tire. However i'm getting the fenderlips rolled this week.

Heres my problem, with a 26 inch tire im getting to almost 6k rpms and in 4th gear by the time i make it to the end of the track. I'm afraid that i'm loosing power after the horsepower drop off at 5700 or so rpms. So i was looking at getting a 275/60/15 tire. which would be a 28. I don't think my car has enough power to essentially use all of that 28 inch tire, but i thought that it would help my car be in a lower rpm in 4th gear at the end of the strip. What should i go with? let me know
thanks, al

 

[ninjastang125]

I use a 26 inch tire for an all motor 2v. I think a 28 inch tire would make you bog off the line

 

[famousfamily32]

yah that's what i was figuring, thanks

 

[ChillPhatCat]

I don't think that lowering your effective gear ratio is going to make you faster. JMO. Only reason to do that would be if you're getting excessive spin off the line.

 

[ninjastang125]

You change the tire size to a taller tire to lower your trap rpm. If he was afraid of running out of gear he could change tire size instead of gears. So no not really to go faster,

 

[famousfamily32]

yah i dont plan on having a 28 inch make it faster, just to lower my rpms. I'm going to the strip this weekend on the 26s i have now and i'm going to see what my rpms reach to figure out what i'm going to need to do. But like ninja said i think 28 would be a little steep for my car on the launch

 

[BannonJr]

Yea...I ran 28's 2wice...bogged like hell..

Switched to 26's and gained alot...

 

[98COBRA281]

i run 26" M/T's, and trap at about 6200rpms, at 110mph with 4:30 gears......

 

[SteveR]

2" taller tire will drop your 1320' rpm by about 300-400 and slow your 1/4 mile time by 6-10 hundredths depending on your setup. If it's an auto a good stall converter will help with the 60' times with a taller tire or if it's a stick launching higher.

 

[Midnight2V]

This post is a little off topic so I apologize in advance, I just wanted to offer a different idea.

If you are worried about going beyond your power band, why not extend it with a set cams? Not only do you shift your entire power band into your operating range but your post peak power will be greatly improved. Yeah you lose a little bottom end with a stage 2 or higher, but you're never really in that range on your application anyway.

What do you think?

 

[famousfamily32]

Thanks guys. Yah I would like to do cams but is it a pretty extensive project on 2vs?

 

[bhuff30]

It is perfectly fine to be just above your power band as you cross the traps. In fact, it is better. The earlier part of your run has MUCH MUCH more impact on ET that the later part, so even if you are out of the power band at the top end, the difference is tiny. Don't change anything, you'll be slower. If you want to be faster, think about the first 330ft and how to improve it.

 

[famousfamily32]

Good advice, thanks a lot man