No, axle CL to the ground X2. Thats the accurate way to do it by measuring.
Or calculate it out like Blaine
RPMs aren’t lining up with GrimJeeper gearing calculator
- Thread starter Bbrayden85
- Start date
Or calculate it out like Blaine
@Bbrayden85
Read this post. It will explain why your Grimm Jeeper results don't match your observed results and describe how to measure your existing tires to work with the gear calculator:
https://wranglertjforum.com/threads/tire-size-measurement-methods.38648/page-5#post-641879
Read this post. It will explain why your Grimm Jeeper results don't match your observed results and describe how to measure your existing tires to work with the gear calculator:
https://wranglertjforum.com/threads/tire-size-measurement-methods.38648/page-5#post-641879
And before you go down the rabbit hole of trying to figure out the effect of altitude and ambient temperature on your tire pressure, read this:
https://www.coyoteents.com/temperature-and-tire-pressure/
https://www.coyoteents.com/temperature-and-tire-pressure/
It really doesn't have to be this hard. Nothing has to be measured. Observe a specific verified MPH. Note the matching RPM. Punch those numbers into the calculator with accuracy on the other parameters and then alter the tire size until the calculator results match what you observe in the vehicle. That is your tire size for the purposes of the calculator.
True, but measuring actual speed and rpm with a drive down the highway will confirm the tire diameter that was extrapolated for those of us who are doubters and those of us old enough to remember Ronald Reagan's sage advice to "trust, but verify."
Oh well, in that case, let's just make it as confusing as possible with all the extraneous information that just confounds the simpleton further.
Measuring the hub height x2 is a simple way to verify the result from adjusting the tire size on the calculator. The two measurements will be very close to each other because the two processes are the same.
In regards to Toe-in adjustment and tire size. How important is it to get the exact tire size when adjusting/checking your toe-in? 1/8" to 1/16" is a pretty small measurement, and I've always wondered about that. Can the tread wear down an 1/16 of an inch and now possibly your toe-in will be off? Can you be at 30psi and set the toe-in, and then air down and now its out of tolerance?
Or am I just splitting hairs?
Sorry for the derail, just curious.
Or am I just splitting hairs?
Sorry for the derail, just curious.
Let's go further down the rabbit hole. How far in front and behind axle centerline are you measuring that 1/8". One foot? Three feet?
Grimmjeeper calculator is not a gear chart.
Ok. Was the value entered for 5th gear correct? A 400 RPM difference sounds like it could be the difference from 1;1 to OD.
No idea, but if you go look at it, it don't take long to figure out it is just basic math with one variable that proves the rule of garbage in, garbage out.
Go look, seriously.