Hook Posted August 24, 2011 Share Posted August 24, 2011 I'm considering swapping the alloys for steel wheels this winter after I bust two alloys £300 last year, and fitting winter tyres. I understand that I can't swap 15" alloys for 15" steels without affecting the speedo or something. I don't really understand this, can somebody explain in layman's terms what I need to do? Ta, Dan Quote Link to comment Share on other sites More sharing options...
iNath Posted August 24, 2011 Share Posted August 24, 2011 It's not just the size of the wheel that's important - it's the combination of wheel, tyre size & profile. The circumference of the tyre ideally needs to be within 2.5% of what it is now. Use this calculator to work out what you can have. I use 195/45/R16 tyres on my 16" alloys then 195/50/R15 winter tyres on my 15" steel wheels which is -1.01% different. According to the calculator Speedo reads 70mph your actual speed will be 69.29 mph Quote Link to comment Share on other sites More sharing options...
wealdman Posted August 24, 2011 Share Posted August 24, 2011 That speedo link took me to an altogether unexpected destination! Edit: it no longer appears as a link, ignore this post. Quote Link to comment Share on other sites More sharing options...
Hook Posted August 24, 2011 Author Share Posted August 24, 2011 Thanks, so I do I need to keep the 195 the same, potentially get 14" steels and then try get as close as poss to 2.5%? Quote Link to comment Share on other sites More sharing options...
PumpkinSteve Posted August 24, 2011 Share Posted August 24, 2011 Thanks, so I do I need to keep the 195 the same, potentially get 14" steels and then try get as close as poss to 2.5%? No, you don't need to keep the 195 part the same. You can use 175/65/R14, 185/55/R15 etc... both of those are within 1%. Quote Link to comment Share on other sites More sharing options...
matty076 Posted August 24, 2011 Share Posted August 24, 2011 i must be useless lo, i just have car to get from A to B Quote Link to comment Share on other sites More sharing options...
Nay ZS Posted August 24, 2011 Share Posted August 24, 2011 If I wanted to keep my current 17 inch alloys on with winter tyres mounted could I use another size other than 205 17 40 if necessary? Maybe 215 17 45? A quick read up online shows some Bridestones LM's and Pirelli Sottozeros are available 205 17 40 but there are far more options with the 215,45 profile. Quote Link to comment Share on other sites More sharing options...
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