TommyDUB Posted October 21, 2013 Report Share Posted October 21, 2013 Hi all,I'm a complete newbie when it comes to tyres, I'm currently running 175/65/r13 (standard on most lupo's) and I want to put 15" alloys on with a 195/45/r15 tyre.Question is, will I need to correct my speedo? If so, does anyone know anywhere that would do it?Many thanks people!TD Quote Link to comment Share on other sites More sharing options...
Deadmetal Posted October 21, 2013 Report Share Posted October 21, 2013 They'll be a 0.22% change in speedo reading.I don't think they will be any point in messing with your speedo reading for that. Quote Link to comment Share on other sites More sharing options...
TommyDUB Posted October 21, 2013 Author Report Share Posted October 21, 2013 Well thats cleared that up, thanks very much for the reply! Quote Link to comment Share on other sites More sharing options...
treblet Posted October 21, 2013 Report Share Posted October 21, 2013 As Deadmetal's said your speedo will over read.If you go sticking tiny wheels and low profile tyres on you'll run the risk of being done as the speedo will read less than you're actual speed.That said, you'd probably have to put wheels that are so small you wouldn't get them over your brakes to manage that much of an under read. Quote Link to comment Share on other sites More sharing options...
TommyDUB Posted October 21, 2013 Author Report Share Posted October 21, 2013 As said 15"s with 195/45/r15, so not too small haha, so theres no need at all to fiddle about with the speedo? My mates got a fiesta and he reckons putting 15's on his car makes him read 5mph too low, (so he'd do 35 in a 30 zone). Quote Link to comment Share on other sites More sharing options...
Deadmetal Posted October 22, 2013 Report Share Posted October 22, 2013 It'll be the wrong tyre size that messes with the speedo.If you go up in wheels size and down tyre sidewall height the right amount then the over all diameter can be pretty much the same as standard. Quote Link to comment Share on other sites More sharing options...
Botanic Posted October 22, 2013 Report Share Posted October 22, 2013 There are several calculators for this on the Internet.I found this with google for example:http://www.miata.net/garage/tirecalc.html Quote Link to comment Share on other sites More sharing options...
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