What do i change the edge tire size to for 305/55/20??
Thanks guys

 

Do you have a manual? There is a formula in it.

 

No, automatic. 2004 ford f150 fx4

 

I dont have that size tire, but i figure mine out by measuring 1 whole revolution of the tire on my truck. I think its more accurate than the tire calculators. For example my truck has 275/55/20 and the calculator says they have a circumferance of 2545mm, however when i measured i got 2480mm. There is some squish factor but rim size and tire brand come into play also. Hope this helps Here is a calculator: http://www.1010tires.com/TireSizeCal...?action=submit

 

Somehow, I don't think you are joking. I mean an Edge manual. It's on page 16. If you don't have one, I would suggest going to the Edge site and printing one out.

 

wow, sorry just read it again, i read too fast. lol. so does 2649mm sound right??

 

Yes, that is the accurate method. And, when you do the calulation, you should deduct about 5% for squish.

 

ok, I did the math on a 305/55/20 and with their formula, I got 2650. If you allow 5% squish, that would leave you 2517. Try that.

 

ok thanks guys

 

What would my tire circumferance be with 5% squish factor on 305/70 R16? The Edge manual says 2617mm, but I'm alittle off on my speedo.

 

The Edge manual listings nor their formula takes squish into account. You have to reduce their number by 3% to 5% depending on your specific tire.

 

Keep in mind that not all tire brands measure the same, rim width can also come into play as well. So your most accurate answer with be measuring 1 full rotation. If you dont have a metric tape measure just measure in inches and convert it either online or most cell phones have conversion calculators.