Moderators BarManBean Posted December 10, 2012 Moderators Share Posted December 10, 2012 I have questions regarding changing tire size and the effects on a subaru. Specific example has to do with a friend's WRX. His stock tires are 235/45, and he's thinking of picking up a set of winter tires that are 205/45 (different set of wheels). Since all the tires will still be the same size, will this cause any differential issues, or only speedometer / mileage issues? (Paging BAC...) "Bullet-proof" your OEM TMIC! <<Buy your kit here>> Not currently in stock Link to comment Share on other sites More sharing options...
iNVAR Posted December 10, 2012 Share Posted December 10, 2012 differentials will be fine. small/larger overall diameter = speedometer will be off. a smaller wheel will result in your speedo reading too low. a larger wheel will result in your speedo reading too high. and so there's no confusion, the way i use the terms are: tire = rubber rim = the thing the rubber goes around wheel = tire+rim mounted together Link to comment Share on other sites More sharing options...
Moderators BarManBean Posted December 10, 2012 Author Moderators Share Posted December 10, 2012 differentials will be fine. small/larger overall diameter = speedometer will be off. a smaller wheel will result in your speedo reading too low. a larger wheel will result in your speedo reading too high. and so there's no confusion, the way i use the terms are: tire = rubber rim = the thing the rubber goes around wheel = tire+rim mounted together Cool. I think that's backwards though. Larger wheel means the speedo will be reporting a number that is actually lower than real life, correct? "Bullet-proof" your OEM TMIC! <<Buy your kit here>> Not currently in stock Link to comment Share on other sites More sharing options...
krzyss Posted December 10, 2012 Share Posted December 10, 2012 The minor problem: OE wheel size is 17 I believe . What is the other wheel size? 205/45 may have this additional problem of too low load index. Krzys Link to comment Share on other sites More sharing options...
Moderators BarManBean Posted December 10, 2012 Author Moderators Share Posted December 10, 2012 Both sets of wheels are 17s. "Bullet-proof" your OEM TMIC! <<Buy your kit here>> Not currently in stock Link to comment Share on other sites More sharing options...
mr.hicksta Posted December 10, 2012 Share Posted December 10, 2012 Boom. http://www.1010tires.com/tiresizecalculator.asp Link to comment Share on other sites More sharing options...
iNVAR Posted December 10, 2012 Share Posted December 10, 2012 Cool. I think that's backwards though. Larger wheel means the speedo will be reporting a number that is actually lower than real life, correct? yeah, sorry, i had it backwards. Link to comment Share on other sites More sharing options...
Moderators BarManBean Posted December 10, 2012 Author Moderators Share Posted December 10, 2012 Boom. http://www.1010tires.com/tiresizecalculator.asp Does not answer my question I have my own spreadsheet set up to calculate the overall outside circumference anyway. "Bullet-proof" your OEM TMIC! <<Buy your kit here>> Not currently in stock Link to comment Share on other sites More sharing options...
Aracheon Posted December 10, 2012 Share Posted December 10, 2012 Boom. http://www.1010tires.com/tiresizecalculator.asp Beat me to it. Link to comment Share on other sites More sharing options...
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