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Squeezing 295s in to the rear


RorySolow

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Evening folks,

 

So it's payday again, and this month is bonus month! What better way to spend it all than on Z bitz? :wacko:

 

I've wrapped my rear Linea Corse LC818s in Pirelli 295/35s, with some great results:

 

IMG_2333.jpg

 

On Saturday the car's going to Style Dynamics for a custom quad exit exhaust. Something like this...

 

36672d1158923429-quad-exhaust-outlet-img_1561.jpg

 

Thoughts?

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I am afraid I go the other way, like the quad tips, but 295 is way over tyred, ride and handling will suffer.

 

Actually I've found the opposite. With 295s it's very difficult to go sideways! Maybe I should fit some bicycle wheels to the back? ;)

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Just to clarify, I can't see how the ride would suffer - surely bigger tyres = better ride. I can agree that it could potentially introduce too much understeer or make the rear of the car feel very 'dead', but that's dependent on a lot of other things.

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Well, I got tramlining on the stock 225/45 245/45, and I still get it now on 255/35 285/35. I haven't decided if it's worse or not yet, but so far it hasn't done anything truly alarming. It would be down to front tyre size anyway, yes.

 

Regarding the exhaust, I think the quad pipes look pretty good, although I don't think I'd go for it (which is a bonus IMO, because it would be boring if we all did the same stuff).

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I am afraid I go the other way, like the quad tips, but 295 is way over tyred, ride and handling will suffer.

 

Actually I've found the opposite. With 295s it's very difficult to go sideways! Maybe I should fit some bicycle wheels to the back? ;)

 

I dont seem to suffer with traction @ 400hp on a 275, you can get any car to go sideways, tyre size is immaterial ;)

 

Wider the better. I'm running 305 on the front with 345 to the rear :p

 

Bet she handles a treat.....on the drive :stir:

 

There is a reason car manufacturers just dont slap the widest tyres they can on a car, its called balance. There is so much more to consider, weight over the tyre, contact patch, geometry, front tyre sizes. You would probably get more traction from fitting a sticky 275.

 

Certainly not a hater, just see no plus's to the minus's :)

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in basic terms, the area of the contact patch will stay the same - all the fitting a wider tyre will do is change the shape of the contact patch - it will be wider, but not as long. therefore better for lateral cornering, but worse for acceleration and braking. and in basic terms, the contact patch size is dictated (in simple terms) by car weight and tyre pressure.

 

the total grip is simply a factor of the force acting on the tyre (the weight) multiplied by the coefficient of friction for that tyre. regardless of the width of the tyre. so yes, you would be better fitting a sticky tyre rather than a wider tyre, as a sticky tyre does actually have a higher coefficient of friction.

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Love the tyres Rory as cars like the Zed really suit wide rear tyres imo. B):cloud9:

 

 

 

One thing I do wonder though (and maybe Ekona can answer this or someone else more up on their tyres than me) with you having a 295 tyre shouldn't you have lowered the profile down to 30?

 

Only reason I even question it is because I used to run with 245/35/19 up front and 275/35/19 on the rear which I was told wouldn't mess up my traction control system (it didn't). When I enquired (with an alloy wheel/tyre trader) about putting 285's on the rear instead of the 275's I'm pretty certain he mentioned that firstly I'd need 255's upfront instead of the 245's then but I would also need to bring the profile down to 30 as it is essentially an aspect ratio, so the width of the tyre directly effects the height of the side wall.

 

Maybe it's different though if yours are 18's and it's still within the parameters that the TCS works in. :thumbs:

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Profile is a percentage of width, yes... I'm not sure at what point the TC throws a wobbler, but 295/30 is closer in diameter to 255/35 than 295/35 is (295/30 is a 0.23% difference in diameter to 255/35), so I guess it would make sense.

 

They'll be 19s in the OP anyway. 35 profile on an 18" rim would be a tiny diameter.

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One thing I do wonder though (and maybe Ekona can answer this or someone else more up on their tyres than me) with you having a 295 tyre shouldn't you have lowered the profile down to 30?

 

Only reason I even question it is because I used to run with 245/35/19 up front and 275/35/19 on the rear which I was told wouldn't mess up my traction control system (it didn't). When I enquired (with an alloy wheel/tyre trader) about putting 285's on the rear instead of the 275's I'm pretty certain he mentioned that firstly I'd need 255's upfront instead of the 245's then but I would also need to bring the profile down to 30 as it is essentially an aspect ratio, so the width of the tyre directly effects the height of the side wall.

 

You raise an interesting point mate. I hadn't thought of this... So a quick bit of research shows the OEM spec for the Track Edition Z (Front: 225/45/18 / Rear: 245/45/18) has an 18mm (2.73%) difference in diameter. My current spec (Front: 245/35/19 / Rear: 295/35/19) has a 35mm (5.35%) difference in diameter. Whoops! I'd better make some adjustments!

 

Looks like fattening up the fronts won't come that close to matching either... if I go wider to 255 it'll still be 28mm (4.24%) out :scare:

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I guess the best option would be 245/40/19 up at the front. That'll take me down to 10mm (1.47%) difference.

 

Visually your car might look a bit odd though.

 

True dat. Well, if I'm 5% out at the moment and everything is irie, then I'll just whack 255/35 on the front and be done with it.

 

Thanks all for opening my eyes to tyre height. :blush:

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And then your 19mm out on diameter from oem, 225/45, 2.88%, so your tc will throw a wobbly.

 

245/35 is the right front tyre for 19's.

 

Out from OEM won't affect TC, as long as the front:rear ratio is correct. It will make your speedometer read incorrectly though.

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