Will this tire size change affect my speedo?
06-18-2003, 02:17 PM
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Will this tire size change affect my speedo?
Replacing factory 215/60/15's on my 83 944 with 225/45/17 front and 255/40/17 rear. Will this affect my speedometer reading and my RPM's? Thanks.
06-18-2003, 10:56 PM
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calculate away!!!>>> <a href="http://www.miata.net/garage/tirecalc.html" target="_blank">http://www.miata.net/garage/tirecalc.html</a>
06-22-2003, 09:32 PM
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</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by blindeye:
<strong>Replacing factory 215/60/15's on my 83 944 with 225/45/17 front and 255/40/17 rear. Will this affect my speedometer reading and my RPM's? Thanks.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Hi Blindeye,
No difference in your speedo - Porsche uses 25" as the stock outside diameter for our cars - so the 17s are virtually identical to your 15s in overall diameter.
Normal wear on these tires will account for a slight variation in your speedo anyways, so no need to be concerned.
BTW, the rear 17s are stock Porsche size for several models.
<strong>Replacing factory 215/60/15's on my 83 944 with 225/45/17 front and 255/40/17 rear. Will this affect my speedometer reading and my RPM's? Thanks.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Hi Blindeye,
No difference in your speedo - Porsche uses 25" as the stock outside diameter for our cars - so the 17s are virtually identical to your 15s in overall diameter.
Normal wear on these tires will account for a slight variation in your speedo anyways, so no need to be concerned.
BTW, the rear 17s are stock Porsche size for several models.
06-26-2003, 12:14 AM
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Thanks guys! Thats a great calculator. Could have really used it when my son went from BFG All Terrains to 31" Super Swampers on his ZJ. Oh well, 2 tickets later.....
Thanks again.
Thanks again.
