does anyone know what a 305x60x18 is on the edge programmer?

thanks

 

2490 cm.

The formula used is:
[(tread width x aspect ratio x 0.02) + (rim diameter x 25.4)] x 3.1416 x 0.97. Plugging in your tire sizes, aspect ratio, and rim diameter, we get:

[(305 x 60 x 0.02) + (18 x 25.4)] x 3.1416 x 0.97 =
[ 366 + 451.2 ] x 3.1416 x 0.97 =
2490 cm.

The formula is a basic formula for finding the circumference of a tire, found in the Edge manual. The 0.97 is a tire squish factor.

Hope this helps.

 

thanks for posting that, I need to change mine too I suppose. I went up from the stock 17s to the 20 inch OEMs with the 275/55r20 Scropions, It is very important to change this right away?

 

Only if you want your odometer and speedometer to be accurate.

Keep in mind that the speedometer will always read a little (2-3 MPH) high even if your tire size is correct.

If you're interested, I created a spreadsheet that will calculate tire dimensions and revs/mile (including columns for the squish factor). PM or e-mail me and I'll send it to you.

 

Glad I could help someone with my knowledge, tman07f150. Sometimes it is just easier to show someone how to do it than to tell them where to find the information.

Must have been the nice weather down here and a couple of MGDs that made me nicer; of course, could have been the Preparation H bath that converted me from a PITA to a nice guy.

 

MGD v4.1

 

Your influence is spreading like wild fire!

 

I haven't been promoting Preparation H!

Perhaps I should be! Put those flames out!


MGD v4.2

 

I'm going to make one TINY correction to your otherwise excellent (post-Preparation-H entry): The answer is in millmeters (mm), not centimeters (cm).

If your result was really in centimeters and was correct, the tires would have a diameter of about 26 feet!

Welcome to the "off by ten club". I made a post like that in the electrical forum not too long ago. :o

- Jack

 

thanks guys helps out a lot i almost had by doing a regular circumfrence formula 2(3.14)R i was just alittle off

 

I should have caught that with the 25.4 multiplier. One too many MGD "brain lubricators", I guess.

Thanks for the correction, Jack.