I changed my tire size due to the MT drought we have been having. I went from a 25.8 inch 315/35/17 to a 295/45/17 and its killing my track times. I'm about 2 mph slower on the 1/4 times. Is this normal? Where can I find a calculator that will let me see whats going on. I've either got to go back to shorter tires or restall the convertor or anybody else got any ideas?

 

Maybe a taller gear....

 

He now has a taller tire so a taller gear would just make the situation worse.

I you are getting great traction i would go bigger on the stall. But a bigger stall may also lower the mph, but should in return lower you et as well.

Did your actual et time get worse? Don't forget that air temp and humidity have a big factor on power.

 

try the calculator in my sig it may help you figure out what is going on. It showed me that I had the same results running 3.73's and 28" (275/60 15's) tires then I would have running the stock size tire with 3.42 gears...

You change took you up ~ 2" as well, from 25.68" to 27.45", meaning you dropped about the eqivalant of a gear size, so that may be your issue and may cause shifting timing issues as well...

 

I have a tire queston as well sorry to invade your thread

I am using 26 inch et drags right now and I am wondering at 12 psi how much they grow on the big end compared to 28 inch et radials(17psi) at 130mph
will the difference on the gear calculator be the full 2 inches or less

 

does anyone read the stickeys anymore?

 

We will find out tonite for sure. Its T&T nite tonite and we got 55 degree weather promised. Last time I ran it the temp was about 100 degrees in the shade and it was actually spark knocking running 93 octane.But I know the car is hitting the power band around 4200 and my vigalante will stall to about 3800. I'm thinking that extra 1.5 inchs of tire has got me screwed up. You gotta realize that for every revolution thats 4 inchs extra. What this animal needs is about a 200 shot of NOS to wake it up.

 

I have read it, but the one I have is more robust then the f-body.org gear calculator in the sticky, although they are similar...

 

does anyone know how much a 26 inch et drag swells to on the big end compared to a 28 inch et dragradial?

 

When I was drag racing I would use a lower gear like a 4.10 vs. 3.90. Then I found that I could use a high growth tire to make up the difference in gear ratio at the top end.

Now this being a door car and tire selection might be different too. I have had good luck running that way. My best times with a dragster of course was 6.97 @ 198MPH. Oh what fun that was.