SamuraiFlash Posted July 14, 2012 Share Posted July 14, 2012 My tyres will need changing on the rears very soon, I currently run 275 35 18's and I'd like to go to a set of 275 40's for the higher sidewall. If I was to change there will be a rolling radius change of +4.15%, in what way will this affect my car apart from the speedo and have you guys had any issues? I just like the look of a fat sidewall and the comfort will be a bonus, any pics would be appreciated. Thank you Quote Link to comment Share on other sites More sharing options...
dan294 Posted July 14, 2012 Share Posted July 14, 2012 http://www.mkivsupra.net/vbb/showthread.php?233707-Project-Supracharger/page44 David P has them on his Supra. Don't look that bad. Quote Link to comment Share on other sites More sharing options...
David P Posted July 14, 2012 Share Posted July 14, 2012 (edited) 275 40 18 on 10J stock height. 285 40 18 on 10J lowered 10mm, lip trimmed @ top. Plenty more pics in 'my garage'. Edited July 14, 2012 by David P (see edit history) Quote Link to comment Share on other sites More sharing options...
SamuraiFlash Posted July 14, 2012 Author Share Posted July 14, 2012 Thanks for the pics David, did you have any problems with the 275 40 18's in terms of them rubbing the arches etc? What are you running at the front btw? Quote Link to comment Share on other sites More sharing options...
johnny g Posted July 14, 2012 Share Posted July 14, 2012 I'm thinking of 285/40/18 next on my TTE wheels. Bit more predictability over the 285/30 Quote Link to comment Share on other sites More sharing options...
David P Posted July 14, 2012 Share Posted July 14, 2012 (edited) The rear lips have been trimmed to the centre of spot-welds at the top so there was no problem, but it would be touch and go without. It will be dependant on your wheel size and offset, these are 10J ET 45. This might help. http://www.1010tires.com/WheelOffsetCalculator.asp The fronts are 8.5J ET 40 with 245 40 18. All this info is in my garage, you just need to pluck up the courage to press a button and look. Edited July 14, 2012 by David P (see edit history) Quote Link to comment Share on other sites More sharing options...
David P Posted July 14, 2012 Share Posted July 14, 2012 I'm thinking of 285/40/18 next on my TTE wheels. Bit more predictability over the 285/30 The improvement in the ride is very evident. Quote Link to comment Share on other sites More sharing options...
johnny g Posted July 14, 2012 Share Posted July 14, 2012 The improvement in the ride is very evident. Thanks, David. I look forward to it. Quote Link to comment Share on other sites More sharing options...
garethr Posted July 14, 2012 Share Posted July 14, 2012 If you rely on speedo error to drive at a "real" 30/40/50/60/70, just remember that the higher gearing leaves you less of a margin. 285/40-18 will probably make the speedometer almost accurate. Quote Link to comment Share on other sites More sharing options...
David P Posted July 14, 2012 Share Posted July 14, 2012 Pull the needle off the speedo, find 70mph with Satnav and pop it back on @ 70 then you know it's correct. Quote Link to comment Share on other sites More sharing options...
CanisLupus Posted July 14, 2012 Share Posted July 14, 2012 275/35 is almost stock rolling radius. 275/40 will be out by 4% as SamuraiFlash said and 285/40 would be even more out(5%). The Speedo could be showing LESS than you are actually driving with both sizes! 275/35 100mph 275/40 96mph 285/40 95mph Quote Link to comment Share on other sites More sharing options...
garethr Posted July 14, 2012 Share Posted July 14, 2012 Depends what you're comparing against, of course. If it was originally a J-spec TT you could be almost 10% out. 225/50-16 0.00% 275/40-18 7.3% 285/40-18 8.5% 245/45-16 0.00% 275/40-18 8.0% 285/40-18 9.3% 255/40-17 0.00% 275/40-18 6.5% 285/40-18 7.8% Speedometers invariably over-read on the stock size. Quote Link to comment Share on other sites More sharing options...
David P Posted July 14, 2012 Share Posted July 14, 2012 This pic is a better view of clearance with 275 40 18's and stock height suspension. Quote Link to comment Share on other sites More sharing options...
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