4RE Leather Posted September 20, 2011 Share Posted September 20, 2011 It can be very unnerving when it happens and TCS in the 350z isnt exactly subtle so I can see why it'd scare the crap out of anyone I had to do it on my old 350z when swapping some wheels around and had my Rotas at the rear and Rays the front. They were both 18" wheels but the Rotas had a lower RR on them (by design and recommendation of an old trader on here), which was fine with all 4 Rotas as the RR front to back compensated, but with Rays on the front the TCS went mental, very unnerving I learnt a lot about how the TCS worked that day after thinking my car was broken Does this mean that if it does it again when I put the 275/40/18 on the frear and the oem rear 245/45/18 on the front It might throw another wobbly? And if it does instead or taking the rears off this time. Put the 225/45/18 oem back on the front! I am now officially on Prozac and class 1 pain killers as my brain just fryed!!! Quote Link to comment Share on other sites More sharing options...
Chris`I Posted September 20, 2011 Share Posted September 20, 2011 OEM - 225/45/18 and 245/45/18 gives a 2.73% difference. (think thats the OEM sizes, been a while since I did this) 275/40/18 and 245/45/18 gives a 0.15% difference between them, so its likely to throw a wobbler. 275/45/18 and 245/45/18 gives a 3.83% difference which from what I remember sounds about right, but might be too much the other way. You ideally want about 3% difference as it is with the OEM setup. Quote Link to comment Share on other sites More sharing options...
4RE Leather Posted September 20, 2011 Share Posted September 20, 2011 OEM - 225/45/18 and 245/45/18 gives a 2.73% difference. (think thats the OEM sizes, been a while since I did this) 275/40/18 and 245/45/18 gives a 0.15% difference between them, so its likely to throw a wobbler. 275/45/18 and 245/45/18 gives a 3.83% difference which from what I remember sounds about right, but might be too much the other way. You ideally want about 3% difference as it is with the OEM setup. Thats exactly what the tyre Bible says. However they have ordered the tyres and swear it will be OK. I am really starting to loose it big time because what one would think would be an easy task has turned out to be a troublesome nightmare. Quote Link to comment Share on other sites More sharing options...
Chris`I Posted September 21, 2011 Share Posted September 21, 2011 What you need to confirm with them is that they know the rolling radius of the front and rear tyres isnt the same. In 99% of cars it is the same front to rear, but in the Zed it is not. You need to keep this ratio of front to rear rolling radius stagger the same otherwise the TCS will think the wheels are tuning at different speeds (compared to each other) and will throw a wobbler. TCS doesnt care on the actual speed the car is moving, just whether the rears are turning quicker than the front. It is pre-preogrammed to know there is a difference between front and back, if you remove this (as your tyre sizes suggest) then it will think the rears are spinning quicker than the front (in reality they are not) and will kick in. At the end of the day if you tell the tyre place that you want it OEM spec (RR front and rear with a stagger) and they decide to give different sizes then thats their problem and they should change them FoC until it works Quote Link to comment Share on other sites More sharing options...
4RE Leather Posted September 21, 2011 Share Posted September 21, 2011 There is nothing wrong with the oem on the car. I just wanted to widen the backs, to fill out the arches a bit so took the width up 3 sizes. As 275/40/18 only has a 0-07% different I am banking on them working. So I will get them changed the backs 1st and go for a run. Then if I can get away with the 245/45/18 OEM from the rear and put them on the front I will. But the difference between stock 225/45/18 and 245/45/18 is +2.73% Not sure how it's got into such a mess or why such a simple thing should be so complicated. When I got the Zed I joined 2 Forums. This and another. One of them had all the sizes and combinations for the Zed on a chart that a member had compiled. Ask me can I find it? Actually no don't ask. I will print of your input and arm myself with it when i go to the tyre place. Thats if it ever ever stops blooming raining? Even my Tropical fish are hiding!! Peter Quote Link to comment Share on other sites More sharing options...
4RE Leather Posted September 21, 2011 Share Posted September 21, 2011 Ok guys a big thank you for all your input and I have ordered 245/40/18 for the front and 274/40/18 for the back. Thats got to be £1100? Must put the others I took off in the sale section as fronts only done 900 miles a rear 1500. Cheers Peter Quote Link to comment Share on other sites More sharing options...
4RE Leather Posted September 23, 2011 Share Posted September 23, 2011 Ok Folks it's all sorted now and a big thank you to everyone especially Chris`I as I actually understood what he was saying:) One the rear I have the Bridgestones. 275/40/18. And the front 245/40/18. £800 with discount. No traction problems and it really does feel "Planted" it thats the correct word to use. Anyway within 20 mins of putting them on I overtook a slow van on the A217 Banstead By-pass and drove straight over 2 lumps of 4x4 laying slapp bang in my path. I slowed but a double bump at 50mph had me fuming. Glad to say I was extreamly lucky as the only damage was a sprained right wrist and a dent in my ego. Anyway a nice 4 hre drive to Preston tomorrow should run them in. I hear there is a meet for Toyota MR2's and some other jap stuff at the Ace of Spades cafe Sunday week. My mate said he knows of a few Zeds that will attend so I am going along. Might see some of you there! later Peter Quote Link to comment Share on other sites More sharing options...
Chris`I Posted September 23, 2011 Share Posted September 23, 2011 Glad to see its sorted and most importantly no TCS light Quote Link to comment Share on other sites More sharing options...
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