Toyo Proxes R888R is a summer tyre made in total of 18 sizes, ranging from R14 to R14 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 225/40 R18 is 40mm wider than the narrowest dimension (185) and 10mm narrower than the widest one (235). This tyre profile of 40 means the sidewall height of the tyre is 40% of the tyre width (225mm), which results in 90mm sidewall height. In 225/40 R18, there is only one possible speed index for Toyo Proxes R888R - "Y", which is good for speeds up to 300 km/h. Latest test in 225/40 R18 was held by SportAuto in 2017, where Proxes R888R received rating "Highly recommended" and finished on the 2. place. It was tested on a .