Evil_Nuts Posted February 13, 2011 Share Posted February 13, 2011 Well thats nice to know I think ill try it out with a few other tweeks and see how it goes. Question though with a 18 x 9" wheel with a +40 offset would they scrub ? Scrub?? As in on your arches? Quote Link to comment Share on other sites More sharing options...
dr_jekyll Posted February 13, 2011 Share Posted February 13, 2011 its funny this thread has come up at this time , im considdering trying 9.5s all rouund but with a 265 front and a 285 rear. . the easyest way to kill understeer i found was to run slicks , this sorted it , it turned in a speed beutifully, obviously for a road aplication you cant run slicks so adding more tyre at the front could help, i suppose its something that has to be tryed Quote Link to comment Share on other sites More sharing options...
CanisLupus Posted February 13, 2011 Share Posted February 13, 2011 I'm running 235s all round with the winter tyres. No issues in handling so far even when giving it some beans Quote Link to comment Share on other sites More sharing options...
Kirk Posted February 13, 2011 Author Share Posted February 13, 2011 it may work well in killing some of the understeer on the MKIV This is what im looking at trying to achieve as mine tends to wash wide when chucked into a corner a bit hard. Ive always got a problem with front end grip on the 225s Scrub?? As in on your arches? Yup that and the wheel well. Quote Link to comment Share on other sites More sharing options...
Ark Posted February 13, 2011 Share Posted February 13, 2011 (edited) Hey Martin, As stock the NA should run 225/45x16 all round, with a 50 offset. If you stick a 9" wheel on there, you'll need to run a 255 for the tyre not to look stretched, and with that offset you'll hit the arches on compression (depending on stiffness and lowness of course). What kind of tyres are you using ATM? Better rubber might be all you need to fix the understeer. Edited February 13, 2011 by Ark (see edit history) Quote Link to comment Share on other sites More sharing options...
Kirk Posted February 13, 2011 Author Share Posted February 13, 2011 Well to be fair chris mine is probly a couple of mm lower on the front so i dont think that will be an issue. My suspension is full bilsteins coilovers, no idea of the spring rates but when shown abuse they do firm up a fair bit. Better rubber up front may solve the problem but to be honest i want to see what the car reacts like with matching tyre sizes on all corners. Call it experimenting Quote Link to comment Share on other sites More sharing options...
Scott Posted February 13, 2011 Share Posted February 13, 2011 The way I have always understood it is that more rubber is required on the rear due to the fact that when cornering the limit of grip will vary dependant on the power at the rear. Cornering with no throttle will lead to nice safe understeer, having more rubber on the rear will give you a little margin to play... leading to safe understeer over the limit. Having the same rubber on the rear and going into a corner your car will probably be more balanced off throttle but if you aren't careful you have no margin for error. It shouldn't be AS much of an issue with an N/A as you won't have the same sort of torque as the TT but it will still have power going to the rear wheras the front has nil. The reason why the guys in the US might run the same size tyres on all 4 corners will be down to the tyres themselves. They are so wide that they will provide tonnes of grip meaning that there is less requirement for an error margin. I very much doubt they would use box standard 255 tyres on all 4 corners, excellent soft grip wide ass 315s would be awesome Quote Link to comment Share on other sites More sharing options...
pedrosixfour Posted February 14, 2011 Share Posted February 14, 2011 I'm probably going with 9" rims all around, possibly 9.5" on the rear if the 2nd pair of 9" Cr Kai rims I'm hoping to get cheap fall through. For me there is no point in going any wider than 9.5", front or rear, as the tyre widths in the ITCC are determined by the weight of the car but with a 265 absolute maximum. I understand completely why you are considering this change Martin, the Supra is very difficult to push into a corner, the front grip is either there or it isn't and a few mph difference is all it takes to run wide in a corner. Its the initial turn in that really limits the car's cornering ability and I too believe that extra rubber may go some way to addressing this. Mid corner and exit strategies will undoubtedly need rethinking as like bignum & Scott say, the nature of the car's grip balance will change and you may find yourself fighting the rear for control of direction (very much like an overly stiff rear ARB). But its all in the name of fun so get to it and we'll compare notes for adjoining hospital beds! Quote Link to comment Share on other sites More sharing options...
Kirk Posted February 14, 2011 Author Share Posted February 14, 2011 I understand completely why you are considering this change Martin, the Supra is very difficult to push into a corner, the front grip is either there or it isn't and a few mph difference is all it takes to run wide in a corner. Exactly right my friend! Im glad someone has picked up on whats im getting at the nature of the car's grip balance will change and you may find yourself fighting the rear for control of direction (very much like an overly stiff rear ARB). Funny you should mention the rear ARB as this is what im looking at removing and running a slightly stiffer front bar. Its hard to explain but after being in this car with my mate you wouldnt believe just how much sooner he can get on the throttle through the bends and the back end stays completely planted. Definatly something i will be looking into trying out. Quote Link to comment Share on other sites More sharing options...
j_jza80 Posted February 14, 2011 Share Posted February 14, 2011 I understand completely why you are considering this change Martin, the Supra is very difficult to push into a corner, the front grip is either there or it isn't and a few mph difference is all it takes to run wide in a corner. I've never found this on any of my cars, on the limit i've found some mild understeer (except with my single running R888s, I was never able to provoke understeer, just oversteer when pushing much further than is really suitable on a public road) If you're finding it hard to push into a corner, you either need to adress your tyre choice, of go for a full geo check. Quote Link to comment Share on other sites More sharing options...
pedrosixfour Posted February 14, 2011 Share Posted February 14, 2011 (edited) I've never found this on any of my cars, on the limit i've found some mild understeer (except with my single running R888s, I was never able to provoke understeer, just oversteer when pushing much further than is really suitable on a public road) If you're finding it hard to push into a corner, you either need to adress your tyre choice, of go for a full geo check. Don't get me wrong mate I'm not saying that my car is unruly, in fact I've driven it back to back with other supras at the same track day and I'll admit to being rightly impressed with the behaviour of my car in comparison to other road-going examples. Where I find it difficult to get adequate turn-in is one corner in particular at Mondello, the hairpin at the end of the start/finish straight. I come into it, hammer and tongs, brake down to second, turn in and ....nothing. Then a second later it bites and the loud pedal can be used to determine the amount of angle you adopt getting out of it. I firmly believe that a bigger front foot print could cope better with the loading that the left front corner needs to deal with at that particular spot. Here is some footage of my car at Mondello with the very suspension that Martin has now on his car. Its probably not too clear in the clip but there is always a hesitation at the hairpin to turn in but once it does its catch the tail if you can! CHYm_GUifko Edited February 15, 2011 by pedrosixfour (see edit history) Quote Link to comment Share on other sites More sharing options...
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