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914World.com _ 914World Garage _ tires\speedo

Posted by: driver66 Jun 4 2003, 04:47 AM

do you guys know how much 195 60 15 will throw off my speedo ? I just installed them on the front and would like to go all theway around with them ,but want my speedo to remain close as i can. any ideas? and remember i have the old original steel [ vw lookin ] rims

Posted by: dbelleperc Jun 4 2003, 05:53 AM

I have 205/50-15's and at 100 MPH my speedo is only 4 MPH fast so I think it wouldn't throw it off that much at all.

Posted by: jdogg Jun 4 2003, 05:54 AM

Go to this link and calculate it!

http://www.miata.net/garage/tirecalc.html

Posted by: driver66 Jun 4 2003, 11:16 AM

THANKS AGAIN....

Posted by: Porsche Rescue Jun 4 2003, 04:34 PM

jdogg, that Miata calculator is a great tool. I think it would be appreciated if you posted the link as a new thread. I have book marked it for future use. I calculate the % difference in revs/mile between stock size and new size and figure that speedo will be fast/slow by that percentage. Is that correct?

Posted by: seanery Jun 4 2003, 04:39 PM

ok, so what aspect ratio do you put in for 165SR15 tires?

Posted by: Porsche Rescue Jun 4 2003, 04:42 PM

I believe 80 is very close.

Posted by: seanery Jun 4 2003, 04:45 PM

danke