keany Posted March 7, 2014 Share Posted March 7, 2014 I know it's another tyre question but I've been searching on here for an answer that would be understood by a numb nut like me but.... On defender 90 now I have standard issue 5.5inch wide steels with 205/80 r16's. I would like to change to 235/85 r16s (on new wider rims) I understand this will affect the gear ratio etc but what I want to know is will it affect it so drastically that I would need to do something about it? And if so what? If it's a big deal I would prob just stick to what I have! I just prefer tyres a bit more substantial. Quote Link to comment Share on other sites More sharing options...
Ratty43 Posted March 7, 2014 Share Posted March 7, 2014 You can use this calculator to see the effects of tyre size changes http://www.inawise.com/tyre-calculator/tyre-size-calculator.html It gives a 10% change on the sizes you give above, which would give more relaxed cruising. Bit of a dent in off the line performance though, not that acceleration is really an LR strong point anyway! Quote Link to comment Share on other sites More sharing options...
ejparrott Posted March 7, 2014 Share Posted March 7, 2014 I would say no. I went from 205's to 7.50's (equivalent 235) and noted no difference at all when I had the 19J. Fitting 3.54diffs made it think a bit but again, barely noticeable. Quote Link to comment Share on other sites More sharing options...
keany Posted March 7, 2014 Author Share Posted March 7, 2014 Thanks Ratty - I'll order the wheels now. Quote Link to comment Share on other sites More sharing options...
keany Posted March 7, 2014 Author Share Posted March 7, 2014 Thanks ejparrott Quote Link to comment Share on other sites More sharing options...
****inthemud Posted March 7, 2014 Share Posted March 7, 2014 I was would say definitely no. I have had them and all runs beautifully on both 200 and Td5 and matches up with GPS speedo etcetc. Having said that I don't think I've ever had a smaller tyre...my old man has them on his 110 I believe as well. Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted March 7, 2014 Share Posted March 7, 2014 That's a standard size for a 110 so should be fine on a 90. You will probably want to change the speedo drive gear to a blue one to keep speedo accurate(ish). See http://forums.lr4x4.com/index.php?showtopic=2025 Quote Link to comment Share on other sites More sharing options...
muddy Posted March 8, 2014 Share Posted March 8, 2014 Looking at your avatar you have a 300 or td5, 235 85 16 could be a standard tyre size from the factory, you will not need to make any adjustments however I would cross reference your speedo with GPS , sat nav etc to double check it's accurate to within a couple of mph. Will. Quote Link to comment Share on other sites More sharing options...
AMB Posted March 9, 2014 Share Posted March 9, 2014 My 300 110 is factory fit standard with 235/85 R16s. According to GPS, speedo reads approx 8% high. Take care with GPS speedo calibration. If you have a good quality modern GPS it will probably use Doppler and relative satellite position to measure speed accurately. Older/cheaper models calculate speed by assuming straight line motion between position samples, then performing a running average across the calculated velocities. For best accuracy on older models, calibrate on a reasonably straight road and take more than one reading Quote Link to comment Share on other sites More sharing options...
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