Ivaan Posted December 30, 2008 Share Posted December 30, 2008 My 1.6K Roadsport is currently on 14" wheels with 185/60R14 Toyo R888's. This gives a overall diameter of 555mm, and hence a circumference of 1.744m. When sprinting with this set up, I believe I'm loosing time because the car's further down the rev range when exiting the corners, and there's less revs/metre for acceleration. I'm particularily thinking about the last hairpin at Curborough and my slow(ish) speed across the line I'm interested in knowing the circumference of the 13" wheels. Am I correct in thinking that the O/A dia will be approx 25mm less ( given the same profile tyres ), or 530mm, with a circumference of 1.665m. This would be around 5% smaller, and equivalent to a similar lift in hp? I've also questioned the suspension set up in a seperate thread, though the two would obviously be connected. Cheers, Clive Link to comment Share on other sites More sharing options...
Ash.Bailey Posted December 30, 2008 Share Posted December 30, 2008 thats drivers excuse number 57 part b, you are quoting there 😬 😶🌫️ most overcome this problem by using a lower gear chomp chomp chomp If It aint yellow, wonky and wobbly................ 😬 Link to comment Share on other sites More sharing options...
Ash.Bailey Posted December 30, 2008 Share Posted December 30, 2008 ps would fitting 205/60/13" rear tyres have the same effect ? I would suggest carrying 3rd gear through the molehill instead of second....... lots of time to be gained there if you can overcome the thought of oooohhhh I've always done the mole' in 2nd 😶🌫️ If It aint yellow, wonky and wobbly................ 😬 Link to comment Share on other sites More sharing options...
Ivaan Posted December 30, 2008 Author Share Posted December 30, 2008 Perhaps I should say it's a 5 speed box. Clive Link to comment Share on other sites More sharing options...
FlymoFraser Posted December 30, 2008 Share Posted December 30, 2008 Ivaan You can play with tyre sizes to your hearts content here Exiting the final hairpin at Curborough is very tricky and I don't pretend to have a solution for you. However I believe it's far more down to the driving than the profile etc? What speed are you doing across the line? Edited by - FlymoFraser on 30 Dec 2008 19:36:19 Link to comment Share on other sites More sharing options...
Ivaan Posted January 1, 2009 Author Share Posted January 1, 2009 Flymo, Just under 90mph, but with list 1b tyres ( hence class 3 ), should be doing better! Link to comment Share on other sites More sharing options...
Adrian Williams Posted January 1, 2009 Share Posted January 1, 2009 Just under 90mph is about right for a class 3 K. 89mph is the norm for a well driven 6 speed K so if you're getting there with a five speed your exit speed from Fradley is about as good as it's going to get. Adrian Link to comment Share on other sites More sharing options...
Bilbo Posted January 1, 2009 Share Posted January 1, 2009 wonkycustard Think you will find the diameter of a 185/60R14 is almost identical to 205/60/13" here That was rather unexpected when I made that change ❗ Not sure its true with Toyo R888's 'Can you hear me running' ......... OH YES and its music to my ears 😬 😬 😬 1988 200 bhp, 146 ft lbs, 1700cc Cosworth BD? engineered by Roger King, on Weber's with Brooklands and Clamshell wings, Freestyle Motorsport suspension. Link to comment Share on other sites More sharing options...
Ivaan Posted January 1, 2009 Author Share Posted January 1, 2009 Thanks all, Maybe best option is save the £££s for a LSD!!! Clive Link to comment Share on other sites More sharing options...
Tikey Posted January 2, 2009 Share Posted January 2, 2009 Maybe best option is save the £££s for a LSD!!! I think this worked for Malcolm Link to comment Share on other sites More sharing options...
Ash.Bailey Posted January 2, 2009 Share Posted January 2, 2009 thats my point Bilbo If It aint yellow, wonky and wobbly................ 😬 Link to comment Share on other sites More sharing options...
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