[gotomgo]

my stang has 4:30s with 26 inch drag radials i come through the traps bouncin off my 6200 revlimiter i need new drag radials any way so i was thinking bout run 27s or should i go 4:10S with 26s?

[dollarbill]

If the car is a strickly only drag car then get 28" drag radials. I know Mickey Thompson makes a bunch in a 28" size. If its a street car you might not like the look of 28" tire so then you would swap to 4.10s or 3.90s.

[gotomgo]

875 inthe 1/8th i can cover the 1/8 in 8.1 in my 1/4 mile car what gear do you have in your 1/8th car??? 28s will slow me down

[dollarbill]

The 28"s will not slow you down. Your basicly changing the gear ratio with the tires instead of the gears. 28"s grip better too. Thats why the really fast cars use the larger diameter tires.

[gotomgo]

the really fast cars also run really high numericaly gear ratios . when drag racing you want your gear ratio set up so thet when you cross the traps your motor is at the top of its power band and is in its final ger ( 3rd in c4 or 4th in trmemac .me)taller tires do hook better i definetly agree there .and yes changing the tire is like changing the gears how ever i have 4 :30s in it now with a 26(25.9) slick im hitting the rev limiter right b4 traps i need a slight gear change shouldnt switch t 27s be more like 4:10s with my 4:30s as 28s with 4 :30s is like 3:90 3:73 ish i think i will go with 28s in the future when im making more power like i said the object of setting your rear up for racing is to come across the traps damm near maxed out .or am i wrong??? the car i have was a daily driver and an 1/8th mile car i bought it blown up and dented up with trashed interior the cars bst ever was 7.98 in the 1/8 i got the car built an identical motor fixed everything wrong with it and took it to the 1/4 i could be wrong about the gear thing im pretty sure you wana come through the traps screaming atleast thats what justin burcham told me a long time ago(jpc owner and nmra champ manytimes) and if the 28s wont slow me down then explain this....i built a super charged car it would do 1.20s in the 1/4 with 28s and 3:55s i swaped the gears to 3:90 and the car goes 10:90s and come threw the traps screaming

[blueracecar]

i have tried to find a formula to use to calculate gears but all i have ever found is one for street cars. but i do know that old car was built for 1/8 mile with 4.88s and a 28" tire. i was on the limiter at 1000' and i went to a 29" and it was just short of the limiter crossing the finish line.granted i started with a taller tire so going up an inch is more circumference but adding an inch should give you at least 150-250' more before you are on the chip.all of my short times dropped a few hundredths but everything on the big end including mph went up

[gotomgo]

true true my car is by all means not a pwpower house im jus drivein the hell out of it power shiftin and it was put together right im getting ready to order 27s but im thinking bout 28s now though theres a rpm calculator some where on line

[dollarbill]

AFM has calculators in the articles sections up top of screen. If you got the 28"s then you might have a little room to make a little more power. And yes you want to cross the traps at peak power in high gear for optimal performance. I wouldn't mess with 27"s, your gonna have a better overall time, and maybe even a better 60' because of the increased grip. When I get back into racing my 89, I'm gonna use a C4 and 4.10s with my 275/50/15s and see where that gets me. I want set my car up for the 1/4 but still be able do decent in the 1/8. Right now the 3.73s just don't cut it for the small power level I'm at.

[EagleAutosports]

You can try the 27's, see how they do. They should bring down the finish line rpm down a small amount, if it's not quite enough then go to the 28's. You do want it screaming right before the limiter, you'll get your best times that way. It's just a matter of finding what the car likes.