The 235/45-17 tire has a diameter of 25.33". The 245/45 tire has a diameter of 25.68" thus a differential of 0.35". This increase in diameter will only slightly, if not insignificantly, change the speedometer readings, i.e. you will be traveling at a higher velocity than indicated on the speedometer. Theoretically speaking. But since the speedometer reading is already optimistic by approximately 2 mph, that new diameter should put you at an accurate speed.
Width-wise there is ample room to accommodate the additional 0.197” decrease in clearance space between the original tire and the strut.
However the 245/40-17 tire fitted on an 8” rim is the reasonable maximum width for that rim. The optimum rim width is 8.5”. So if you install the 245 tire on an 8” rim you may experience some wear in the center of the tire especially at track pressures, say above 40 psi. On the other hand, if you are thinking of lowering the pressure for the street to say at 35 psi or lower, you may damage the rim, especially if you live in an area with ill-maintained pavement.
The bottom line is that is the 245/45-17 is tire size that I will purchase once I use up the Dunlops at couple of driving schools. Go for it.
Wow thank you very much for that explanation. What if i run a 38 front psi and 36 rear psi. Im planing on getting continental dws. Since 40psi would give me wear in the center and 35 would possibly damage the rim, i think that would be a happy medium. The roads here in jersey arent the best. I just want a little more meat on the tires and maybe close the wheel gap a little bit.
i would mess around with the pressures... i've found that with my summers they like 38psi... 40psi and they loose grip sooner 35psi and they roll onto their sidewalls more/wear faster...
however this will vary from tire to tire so play with it... uh ur tires i mean
different brands/sizes will want different pressures so going by what the manufacturer recommends isnt always the best, its mainly meant for the average person that just drives back and forth and doesnt modify or seek that last bit of grip