revD Posted April 17, 2012 Share Posted April 17, 2012 I have been loving my LGT and decided to take her to the track with my buddies while we learned Buttonwillow in preparation for our next LeMons race. Car + Mods 2005 LGT Sedan, stock springs + Struts (135k), Whiteline sways, STI BBS, 235/45/17 Hankook V12's NOW - Look at this video, I started the day with ~35psi in all tires and the tire movement on the below video is scary. I then increase PSI throughout the day, but can this be due to too large of a tire on the rim or PSI? Definition of rolling a tire: Link to comment Share on other sites More sharing options...
FUIAAE Posted April 17, 2012 Share Posted April 17, 2012 Weak sidewalls are usually from cheap tires. An inexpensive solution is to get 'lower profile' tires. IE Instead of running 215/55/16 Run 225/40/16 The middle number denotes the ratio and changes how much sidewall you have. The less sidewall the more 'stiff' it will feel and be. Link to comment Share on other sites More sharing options...
RabidWombat Posted April 17, 2012 Share Posted April 17, 2012 Most people recommend 225mm max on a 7.5" rim. The V12's do say they work on a 7.5" rim, but it seems like dropping down to 225/45 would help the issue. You'd have a slightly shorter sidewall and a tire width better matched to the rim size. From the tires FAQ: "235/45/17 (tallest tire you could use under the GT due to possible suspension clearance issues, best used with an 8" wide wheel)" Link to comment Share on other sites More sharing options...
FUIAAE Posted April 17, 2012 Share Posted April 17, 2012 Wider tire gives you more surface area which improves grip but with that extra grip you're going to be pushing it harder. @ 225 and going to track days I'd say run a 40. Link to comment Share on other sites More sharing options...
revD Posted April 17, 2012 Author Share Posted April 17, 2012 I thought it might be pushing the 235 a bit even though it is listed on tire rack as OK for a 7.5" the tires were also chuncking and losing pieces all over the place - overall the tires are toast after 4 20min sessions. The tires came on the car, and I do love the Dunlop Star specs, so maybe a set is in my near future @ the 225 width. what PSI do you all run on the track with 17" wheels? Link to comment Share on other sites More sharing options...
FUIAAE Posted April 17, 2012 Share Posted April 17, 2012 hankook for a 'cheap' 17" wheel that will grip. Link to comment Share on other sites More sharing options...
revD Posted April 17, 2012 Author Share Posted April 17, 2012 that is what I was running on the video (Hankook V12) I think I will try something I have experience with. The dunlop star specs have been amazing in my experience (2 sets on a different car) Link to comment Share on other sites More sharing options...
FJuan Posted April 17, 2012 Share Posted April 17, 2012 I've just blown through a set of these tires. They provide excellent grip for the price. The only draw back is the sidewalls are softer than other tires I've own, and I had been running them with 38 - 40 psi in them to compensate for the weaker sidewalls. My wife's balls are delicious. Link to comment Share on other sites More sharing options...
FUIAAE Posted April 17, 2012 Share Posted April 17, 2012 No kidding? Hmmm... Aggressive alignment or no? Link to comment Share on other sites More sharing options...
FJuan Posted April 17, 2012 Share Posted April 17, 2012 You could play with the alignment, but for the size of tire you have on there, I would highly recommend running higher pressures. My wife's balls are delicious. Link to comment Share on other sites More sharing options...
iNVAR Posted April 18, 2012 Share Posted April 18, 2012 Just going to echo what everyone else said. Stock is 215/45/17. You're doing 235/45/17. Your sidewalls are 235*45% = 105.75 mm. Stock is 96.75. Your sidewall is 9mm taller, resulting in your overall diameter being 18mm greater, throwing off your speedo by about 3%. Why are you running 235/45 instead of 235/40? Extra comfort cushioning? Pothole protection? Also, agree with the others. I used to have 225/45/17 on my stock 17x7 rims, and it was bulging a tiny bit. I went back to 215/45/17 to square things off. I also run them in the winter now... Better to have a slightly narrower tire to cut through snow. My summer wheels are 18x7.5 225/40 and they are just the right width. If I were you, I'd go to 225/45 and it should be nice and squared up. Or get larger rims to reduce the sidewall even further... Your call. In conclusion, in my experience: 7" rim = 215 wide tire 7.5" rim = 225 wide tire Link to comment Share on other sites More sharing options...
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