carguyrory Posted July 19, 2021 Report Share Posted July 19, 2021 I am considering doing some testing this weekend with 200TW tires on my 2000 Civic Si with an eye toward running some endurance series events. The consensus seems to be that the RS-4 is the clear leader in durability, and for budget reasons that is the tire I am considering. The smallest 15in RS-4 currently available at Tire Rack is the 225/45R15. My question is this: Does that tire meet the rules requirement with unmodified (rolled but not flared) fenders? Thanks in advance for your assistance. Rory Quote Link to comment Share on other sites More sharing options...
Team Infiniti Posted July 19, 2021 Report Share Posted July 19, 2021 The tire meets specs, it’s up to you to decide rim offset to keep em under The fender, if the top half of the tire is uncovered you need flare or puff your fenders out somehow Quote Link to comment Share on other sites More sharing options...
mender Posted July 20, 2021 Report Share Posted July 20, 2021 Quote Link to comment Share on other sites More sharing options...
carguyrory Posted July 28, 2021 Author Report Share Posted July 28, 2021 Just a quick follow up. RS-4 225/45 fit under the fenders of 2000 Civic with no issues. 41 mm offset on 7 in wide wheel. With and without 6mm spacers. Also, these tires were shockingly good! I’ve been using purple crack SM7s and have not run a 200TW tire on this car before. While the Hankooks could not match the outright pace of (new) Hoosiers, they were very “drivable” and posted very consistent laps over 60 minutes. 10 of my 17 fast laps were within 0.6 secs. All data is from Road Atlanta at 90+ degrees and stifling humidity. YMMV. Someone will want to know, so, best ever lap at RdAtl 1:46.6. Best Hankook lap, 1:48.8 on the 19th lap. 3 Quote Link to comment Share on other sites More sharing options...
Ian Posted July 28, 2021 Report Share Posted July 28, 2021 50 minutes ago, carguyrory said: Just a quick follow up. RS-4 225/45 fit under the fenders of 2000 Civic with no issues. 41 mm offset on 7 in wide wheel. With and without 6mm spacers. Also, these tires were shockingly good! I’ve been using purple crack SM7s and have not run a 200TW tire on this car before. While the Hankooks could not match the outright pace of (new) Hoosiers, they were very “drivable” and posted very consistent laps over 60 minutes. 10 of my 17 fast laps were within 0.6 secs. All data is from Road Atlanta at 90+ degrees and stifling humidity. YMMV. Someone will want to know, so, best ever lap at RdAtl 1:46.6. Best Hankook lap, 1:48.8 on the 19th lap. Personally, I'd want an 8" wide wheel minimum for a 225. 1 Quote Link to comment Share on other sites More sharing options...
mender Posted July 28, 2021 Report Share Posted July 28, 2021 1 hour ago, Ian said: Personally, I'd want an 8" wide wheel minimum for a 225. I ran the 225s on 9" rims. 1 Quote Link to comment Share on other sites More sharing options...
hotchkis23 Posted July 28, 2021 Report Share Posted July 28, 2021 9 hours ago, mender said: I ran the 225s on 9" rims. Same here, they seem to like the stretch. 1 Quote Link to comment Share on other sites More sharing options...
wvumtnbkr Posted July 28, 2021 Report Share Posted July 28, 2021 I'm right there with y'all. 245 on a 10. 1 Quote Link to comment Share on other sites More sharing options...
mender Posted July 28, 2021 Report Share Posted July 28, 2021 (edited) 6 hours ago, hotchkis23 said: Same here, they seem to like the stretch. http://i89.photobucket.com/albums/k224/johnny_3301/IMG_1792_zps596ee481.jpg I remember reading an article about the rapid change in tire width and rim width in the early sixties. IIRC, the tire engineers thought that the tire should be wider than the rim and the rim engineers thought the rim should be wider than the tire. Testing went back and forth with a wider tire then a wider rim, and in the space of about six months the combo went from pretty narrow rims and tires to about double the width, with grip increasing every time. That apparently flew in the face of accepted physics which basically said that the available friction was dependent on the normal force and not the contact area. As they say, the theory says it should work in practice, but if it doesn't, it's time for a new theory. Edited July 28, 2021 by mender 4 Quote Link to comment Share on other sites More sharing options...
Technical Advisory Committee mcoppola Posted July 28, 2021 Technical Advisory Committee Report Share Posted July 28, 2021 I went with 9's, cuz 10's were just a bit too wide for: a) bearing loads that are already overburdened, b) weight c) can run 225's or 245's on them. 1 Quote Link to comment Share on other sites More sharing options...
hotchkis23 Posted July 28, 2021 Report Share Posted July 28, 2021 8 hours ago, wvumtnbkr said: I'm right there with y'all. 245 on a 10. Wish we had points for better hubs....245's seemed to make them an every other race consumable. Yes, I know they are only 2.5 pts.(lobbied against that to no avail), but the car is running the same lap times or better. And not one of us whiny drivers have complained yet! 1 Quote Link to comment Share on other sites More sharing options...
Technical Advisory Committee mcoppola Posted July 28, 2021 Technical Advisory Committee Report Share Posted July 28, 2021 1 hour ago, hotchkis23 said: Wish we had points for better hubs....245's seemed to make them an every other race consumable. Yes, I know they are only 2.5 pts.(lobbied against that to no avail), but the car is running the same lap times or better. And not one of us whiny drivers have complained yet! Same times on 225's and 245's? Quote Link to comment Share on other sites More sharing options...
hotchkis23 Posted July 28, 2021 Report Share Posted July 28, 2021 25 minutes ago, mcoppola said: Same times on 225's and 245's? yep.....actually we went 2s faster on 225's at Road America...That was average times btw, I do not focus on ftd....Gingerman will be an even better test for us to really analyze data. I can only assume that at some point the amount of HP provided by the vehicle to drive the increase in friction comes into play in similar way to drag vs. hp. 225's on 9's just seem to work well for our hp number. Also, wear is identical if not better with the 225s, more uniformity. 2 Quote Link to comment Share on other sites More sharing options...
wvumtnbkr Posted July 28, 2021 Report Share Posted July 28, 2021 42 minutes ago, mcoppola said: Same times on 225's and 245's? Should be in my opinion. 245 will be more consistent with temp and time from my experience. 1 or even 3 lap pace will probably not be effected. 1 1 Quote Link to comment Share on other sites More sharing options...
hotchkis23 Posted July 28, 2021 Report Share Posted July 28, 2021 1 minute ago, wvumtnbkr said: Should be in my opinion. 245 will be more consistent with temp and time from my experience. 1 or even 3 lap pace will probably not be effected. That is what we have found. 245 is just too much stress on suspension. 225 on a stretched wheel works ok, when measured over time. 1 Quote Link to comment Share on other sites More sharing options...
wvumtnbkr Posted July 29, 2021 Report Share Posted July 29, 2021 2 hours ago, hotchkis23 said: yep.....actually we went 2s faster on 225's at Road America...That was average times btw, I do not focus on ftd....Gingerman will be an even better test for us to really analyze data. I can only assume that at some point the amount of HP provided by the vehicle to drive the increase in friction comes into play in similar way to drag vs. hp. 225's on 9's just seem to work well for our hp number. Also, wear is identical if not better with the 225s, more uniformity. I just saw this response. I have thought this many times when I see cars with 150 hp or less with really wide tires. Or, semi wide 17s or 18s. I am sure there is some confluence of vehicle weight, suspension setup, aero, and horsepower that a narrower tire could certainly be faster. Quote Link to comment Share on other sites More sharing options...
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