trackpig Posted January 29, 2011 Share Posted January 29, 2011 Hi I have the standard rays alloys fitted to my car. I want to get rid of the understeer thats present on trackdays, to do this , I am thinking of fitting 245/40/18's all round. I have checked on the online calc's and it seems the 245's will fit on the 8" and 8.5" rims no problem. I am aware there my be TC and ESP issues but what about rubbing or poor steering feel?? Any first hand experience of 245's on the front or opinions out there? Quote Link to comment Share on other sites More sharing options...
Stew Posted January 29, 2011 Share Posted January 29, 2011 Could you not dial out the understeer with suspension settings? What tyres are you running just now? Seems some brands are more prone to understeering than others... Quote Link to comment Share on other sites More sharing options...
Ekona Posted January 29, 2011 Share Posted January 29, 2011 Running the same size tyres all round won't dial out understeer, you'll just get massive oversteer as you'll have shifted the balance too far to the front. Drop the front tyre pressures a couple of psi (what tyres are you running, and what pressures?), and get some adjustable A-arms on the front along with some camber arms on the rear so you can set the suspension up more aggressively first. That's the correct way to get rid of understeer, adding massive tire widths at the front is only going to cause a very unbalanced car which will in turn reduce your track times. Quote Link to comment Share on other sites More sharing options...
trackpig Posted January 29, 2011 Author Share Posted January 29, 2011 I could go for a new set of tyres but I want to buy the right sizes. I am happy with 245 on the rear but was thinking of 235 or 245 for the front. The front geo is not really adjustable unless I purchase A arms. Wider tyres seems a cheap way to increase front grip. Thanks for any info p.s I know vredestein ultrac sessanta are rated on here, but has anyone ran them on track? Quote Link to comment Share on other sites More sharing options...
Neilp Posted January 29, 2011 Share Posted January 29, 2011 When your on track do you readjust your pressures sponge the tyres are warmed up? I've never experienced under steer on the track. What tyres are you using? Even in the wet with re040's I didn't get understeer. I did when using the wrong lines on track but alex came out adjusted what I was doing wrong and from then on I was feeling pretty confident. So could you possibly be using the wrong lines or pushing on too hard for the cars capabilities. If it's the latter then a-arms and a new set up will be required I reckon. Quote Link to comment Share on other sites More sharing options...
trackpig Posted January 29, 2011 Author Share Posted January 29, 2011 I have used a couple of different tyre choices, tyre pressures are dropped to around 34psi hot. I find the rear end planted which can make the slightly less front end grip feel more prominent. I know that coilovers, camber arms and full geo is the best way forward but getting the right tyre size is important. What size tyres do the regular trackdayers use on the their Z's? Quote Link to comment Share on other sites More sharing options...
Neilp Posted January 29, 2011 Share Posted January 29, 2011 225/45/18, 245/45/18 i think mines are. The tyres are fine that size, Its more important about the quality of tyre used. zmanalex runs 600whp through this tyre size i think. If your cars set up for road then to be fair your limiting your track abilities. Even a set of lowering springs will make a difference and give you a more aggressive camber set up and center of gravity. I run 35psi on track. A softer tyre will cause the sidewalls to flex more, so maybe try making the fronts a couple of psi higher than the rear Pm zmanalex or abbey motorsport as both of these guys know more than anyone else in britain about racing zeds probably What type of tyre have you on just now for the track? Quote Link to comment Share on other sites More sharing options...
Stew Posted January 29, 2011 Share Posted January 29, 2011 RJN probably know the most to be fair! Quote Link to comment Share on other sites More sharing options...
Neilp Posted January 29, 2011 Share Posted January 29, 2011 RJN probably know the most to be fair! who's rgn? Ive never heard of them lol Quote Link to comment Share on other sites More sharing options...
Dblock Posted January 29, 2011 Share Posted January 29, 2011 I'm sure the guys who run the wide 18s and 19s run 245 at the front but they also run wider rears. Quote Link to comment Share on other sites More sharing options...
Stew Posted January 29, 2011 Share Posted January 29, 2011 I actually run 245s on the front on my 'flash' wheels. Coupled with 285 rears. I couldn't comment on the difference though as it's not a fair comparison (size and weight) with Rays. Quote Link to comment Share on other sites More sharing options...
Neilp Posted January 29, 2011 Share Posted January 29, 2011 i run 245/35/19 on front and 275/35/19 on the rears for road driving Quote Link to comment Share on other sites More sharing options...
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