DannyH Posted May 1, 2008 Share Posted May 1, 2008 Hi All, I was just looking for some advice, i have the standard Rays wheels on my 350z and the tyres on them are 245 45 18's, i have the opertunity to buy some 255 45 18's, my question is will these be ok??? Will have any problems as thats the last thing i want. Thanks Danny Quote Link to comment Share on other sites More sharing options...
H5 Posted May 1, 2008 Share Posted May 1, 2008 Standard rears are 245 http://www.350z-uk.com/forum/viewtopic.php?t=4361 Going wider than the rim would look wierd, not sure about any safety implications though. Quote Link to comment Share on other sites More sharing options...
Trev-the-Rev Posted May 1, 2008 Share Posted May 1, 2008 They would also alter your gearing and speedomer readings due to the rolling radius being greater. Quote Link to comment Share on other sites More sharing options...
Cool Hand Luke Posted May 1, 2008 Share Posted May 1, 2008 Maybe i'm missing something but how would adding a wider tyre alter the rolling radius? I was under the impression the rolling radius would only be altered if you changed the profile of the tyre (and/or the size of rim) i.e going down to a 40 series tyre or up to a 50 series tyre. Quote Link to comment Share on other sites More sharing options...
Trev-the-Rev Posted May 1, 2008 Share Posted May 1, 2008 The the height of the tyre will alter as you change the overall width. Thats why a 205 45 looks lower in profile than a 225 45. Quote Link to comment Share on other sites More sharing options...
Ekona Posted May 1, 2008 Share Posted May 1, 2008 Yup, the second number is the height of the sidewall expressed as a percentage of the width, which is in mm. Quote Link to comment Share on other sites More sharing options...
Cool Hand Luke Posted May 1, 2008 Share Posted May 1, 2008 Yeah i know that but if you look at his first post he is going from a 245 45 18 to a 255 45 18 - thats not going to affect the rolling radius in my opinion. Quote Link to comment Share on other sites More sharing options...
Ekona Posted May 1, 2008 Share Posted May 1, 2008 Not by much perhaps, but it will alter it for the worse. 45% of 255mm is more than 45% of 245mm. *EDIT* using this handy site, with 255 tyres on the speedo will read 1.3% too slow. Quote Link to comment Share on other sites More sharing options...
Trev-the-Rev Posted May 1, 2008 Share Posted May 1, 2008 Not by much perhaps, but it will alter it for the worse. 45% of 255mm is more than 45% of 245mm. That's quite correct. The end result in this instance will be a slight lengthening of the gearing and a speedometer that reads under. Quote Link to comment Share on other sites More sharing options...
Cool Hand Luke Posted May 1, 2008 Share Posted May 1, 2008 Yeah - it does only seem like a small change cant see it being that noticeable but take the point if it was say an increase from 205 to 245 or something. I'd always stick with the standard sizings anyway Quote Link to comment Share on other sites More sharing options...
z-man Posted May 1, 2008 Share Posted May 1, 2008 There is a difference. 245 x 45 x 18 has an overall diameter of 26.68 inches (678 mm) whereas 255 x 45 x 18 has an overall diameter of 27.04 inches (687 mm) so the difference is 9 mm (1.33%). Quote Link to comment Share on other sites More sharing options...
SAFC99 Posted May 1, 2008 Share Posted May 1, 2008 Stick with the 245's! Quote Link to comment Share on other sites More sharing options...
DannyH Posted May 1, 2008 Author Share Posted May 1, 2008 Thanks for all the replys people, thought i had a good deal aswell. oh well lokks like im still on the hunt lol Thanks again Danny Quote Link to comment Share on other sites More sharing options...
Chris`I Posted May 2, 2008 Share Posted May 2, 2008 A 1% difference in the rolling radius should not effect the TC or anything like that and 255 should be fine for an 8.5" wheel (which Rays are on the rear iirc). All you will find is with wider tyres is a buldging look as it is the widest that the wheel will take. Check with Phil@ESR, Adam@Z1, Kev@Envy for their views, but as far as I can see the tyres will fit. Personally I still wouldnt use them as they just "feel" too wide to me. Quote Link to comment Share on other sites More sharing options...
jonathan73 Posted May 2, 2008 Share Posted May 2, 2008 Depends if you like fat rears - I do. But not on my women! I went with 265 40 18s when my Potenzas becamse slicks. I Had the GT4 wheels though which I believe were 8.5J on the rear; 8J on the front. Quote Link to comment Share on other sites More sharing options...
rmmackfc Posted May 2, 2008 Share Posted May 2, 2008 Doesn't just effect rolling radius does it? The friction coefficient would be higher as there is extra rubber footprint being put on the road. Tyre calculators are the best judge though, as long as the rim will take it. Quote Link to comment Share on other sites More sharing options...
DannyH Posted May 2, 2008 Author Share Posted May 2, 2008 so let me get this riight, i can use 255 45 18 tyres, and also stay safe? and the only effect i will have is my speedo will read 1% slower? Thanks Danny Quote Link to comment Share on other sites More sharing options...
jonathan73 Posted May 2, 2008 Share Posted May 2, 2008 Danny, what REALLY matters is whether your rim width will take a wider tyre. After extensive research I found that my 8.5J rims could take up to 285 but 265 would be more comfortable and not be at risk of popping off the rim when high speed cornering (on a track of course). I believe regular Rays are 8J so you should be fine with 265 and definitely 255. As for the rolling radius..... :yawn: Quote Link to comment Share on other sites More sharing options...
DannyH Posted May 2, 2008 Author Share Posted May 2, 2008 thanks for putting it clear mate, guess ill make an offer on them, thanks again for all comments and advice Quote Link to comment Share on other sites More sharing options...
Senya Posted May 4, 2008 Share Posted May 4, 2008 here is tire calculator with rim width advice http://www.1010tires.com/TireSizeCalculator.asp Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.