Phil99vette

iTrader: (11)

Are there any benefits of going to a bigger gear and bigger tire but still keeping the same final drive to tire size ratio? My car has 3.90s and 26" tires and wondering if 4.10s and 28s would help.
Phil

SScam68

iTrader: (20)

I'm wondering the same thing. I'm currently running 4.30 gears on a 26" tire, I want to know if I would benefit from a 28" tire and a 4.88 gear ratio. That or stepping up the 4.30 to a 4.56 on the same tire.

I'm slow though, running 12.2's on 1.64 60's, just a bolt on car. Going to knock out another 200lbs pretty soon to bring my weight down to the 2800lb range (chassis). The weight should get me into the 11's but I want to know how far I can go with additional gearing.

TS6

iTrader: (41)

I'm sure theres more to it, but one of the advantages is more tire contact patch. One of the disadvantages is more rotating weight from the bigger tire. I would say if you don't need the bigger tire, leave it alone.

mrdragster1970

Here's what I was told over the years, by several people.

Torque multiplication of the gear makes up for the added weight of the tire (which usually is not much) and u should 60' better. The contact patch is important if u need it, we always use the narrowest tire possible that let's us still be consistant. Look at the comp elim guys, they don't all use 17" wide like we do, the 4-6 cylinder low torque guys use only what they have to. We use giant tires because of the 1000 plus torque, not for looks.

I was tought, u want the highest gear possible with the rpm in the lights u want. Just an opinion, hope it helps.

02 Camaro SS

iTrader: (4)

With 4.88 gears at 6000 rpm, you will only be able to do 102 mph on a 28" tire. Or 111 at 6500 if you ever raise the rev limiter. It's almost identical for 26" tire with 4.56 gears. That's way too much gear and/or tire.

WS6TransAm01

iTrader: (13)

I think that when making the gear and tyre choise, what you expect your trap speed to be whould also be a major consideration.

If you know your car is underpowerd and you will only trap 110 then a 4.88gear + 28" tire is fine if your car can only rev to 6500 rpm.

When my car was being built we expected to see a 130-131 trap speed when it was dialed in [to happen this fall ] so we went with a 4.56 gear and a 28" tire. Perfect for 131mph with my 7200rpm limiter.

That taller gear allows the car to come out harder from the line, and the taller tire with a bigger sidewall and bigger contact patch gives me the traction I need to take advantade of the car's gear and power.

in Phil99vette's case, I think the 28's with a 4.56 gear will be beneficial to traction and retain roughly the same ultimate drive tation giving you the same trap speed. You will trap roughly the same MPH, but your ET should improve slightly.

3.90's + 26"Tire ~~ 4.11's + 28"Tire
4.11's + 26"Tire ~~ 4.56's + 28"Tire

Just my $0.02

HumpinSS

iTrader: (1)

I was told to pick an rpm you want your car to cross the traps at and then gear it for that. Also going to a 28 will give you more of a contact patch. with 28's and 4.33 my car crossed the traps around 6400 which was alittle low for me. Now with the 56's i should cross at 6700 right where i want to be as far as my cam is concerned

SScam68

iTrader: (20)

You're not taking into account tire growth. I trap right at 109.7, lets say 110 for arguements sake. Rule of thumb is actual trap speed is approx. 2mph more than your trap, at least for these low speeds. So crossing the last beam I'm doing 112. My light is set right at 6000rpm and just as I cross the beam the shiftlight goes off. Doing the math the tire size at the top is approx. 27". That's an increase of about 3.7%. This is an ET Street.

If I were to run a 4.88 gear ratio on a 28" ET Drag and assuming the tire grows just as much (if not more) then as I cross the stripe it should be about 29". That puts me between 6300-6400rpm as I cross the stripe.

Will I be out of the powerband? Yep, but considering how much time I will actually be out of it compared to the time of the whole run I don't it's going to cost me much if at all.

That's exactly my situation. I'm very underpowered. My car is just a bolt on car but up here the DA is 8000-9000ft in the summer. We're about a full sec slower than the guys at sea level. I'm trying to make it up where I can and a lot of it has come from weight. I've got about another 200lbs still sitting on the table with the first 100 coming off in the next week or so. That and there is a bit more power that I can coax out of the car. When it's all said and done I expect to be in the 112-113 range. Even then the 4.88 and 28" tire is a very viable option.

The question is what is the change going to translate into real world ET? .02? .03? .04 off the 60"? MADMAN?? Any suggestions/recommendations?

JRracing

iTrader: (35)

I just strapped on a set of 28s with 4.11's. I have not made it to the track yet. I have no clue what will happen on the juice. I'm hoping for the top of 4th around 6k to 6.8k.

Last year on 26" et streets, it was 6200 on motor and shifting into 5th on the 150 shot. Thats way I bought the 28s.

LC

I will be experimenting this friday with 4.56s and 28s... if that pair does not cut it.. i will be ready to bump the rev limiter and the 3-4 shift...

SScam68

iTrader: (20)

You got your car running? Where are my pictures!!

Check the account when you have a chance.

My bros ran my car and I uploaded the whole unedited vid. My lil bro that's 100lbs lighter than me cut a 1.62 60' , it was packed so I didn't get a lot of passes, best was a 1.64