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				Tyre speed/load rating
				Posted: Wed May 30, 2007 1:07 am
				by egor110
				Just double checking, if i'm looking at some tyres for 17'' alloys and there marked up 205/40/r17 there no good because the speed ratings too low as i need a s(96) for the rear tyres?
			 
			
					
				
				Posted: Wed May 30, 2007 8:10 am
				by trevd01
				You don't say what the load rating is, but yes it should be 96 for the rears. 
Those tyres are several  sizes too small as well. From memory, 225/45 or 255/40 is right for a 17 inch wheel. 
Loads of recent posts on tyre size - and size check on miata.net.
			 
			
					
				
				Posted: Wed May 30, 2007 8:14 am
				by westonwarrior
				205 = width accross tread
40= ratio of height side wall
r= radial 
17 = size of wheel, diameter
After those Digits there should be 2 more a number and a letter 
IE 96 s
96 being the load rating and s being speed
as long as the load rating is 96 or above and the speed letter is s better you should be ok
there is a fact sheet on tyres in the members only section