gearing questions

[twizted]

Right now i'm running 83-84" around tires with a 6.33 i.n ford 9" and turning 6000 rpm. Going to tires that measure 86-87" around. After going to the taller tires I would like to be able to turn 300-500 rpm.
I was told that for every 0.1 that I go up on gear I would see about 100 rpms on tach as a rule of thumb.

This is a stock body metric pure stock car not a mod but I seem to find more knowledgeable people here. Thanks for input

[speedbuggy]

I have a calculator that can tell you for a given rpm, gear and tire rollout, what the speed will be. You can put in any three and figure out the 4th.

You want to turn less rpm, more or what? In your situation, if you change to the taller tires, keep the same gear, and are going the same speed, you will turn 5800 rpm instead of 6000.

If you keep everything the same except the tires and turn 6000 rpm, you will be going 2.6 mph faster.

Not sure what you are asking...

[HEAVY DUTY]

Putting 3 inch bigger tires will make you 633 gear act like a 600. If you want to turn 3-500 more RPM with the taller tire, you will need to go about 680 a gear

[twizted]

Thank you, I am putting the bigger tire on and wanting to turn another 300-500max more RPMs after tire swap. I was guessing i needed a 6.60 to be safe or 680 to tuen the max. I would be interesting in playing with the calculator

[speedbuggy]

It doesn't look like I can attach a spreadsheet to a post. If someone can tell me how you do that, I can send you the calculator. It has three things:

1) Wheel weights from percentages: you type in the total car weight and left, rear and cross %'s, and it tells you each wheel weight
2) RPM/gear change calculator: you type in old rpm, old gear, and new gear, and it tells you the new rpm for the same speed
3) Speed calculator: you type in rpm, wheel diameter, and gear and it tells you what speed (mph) you are going. I used this one to come up with the numbers I posted above.