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Old 04-21-2014, 03:08 PM   #1
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245x45-17 tires

I have four 245x45-17 Ultra performance tires from my former ride
(2006) Audi TT. 3 months worth of wear on them. My question is
Can I use them on my new 2003 boxster, 17 inch wheels?

2. What is the purpose of using different size tires/wheels on a
Porsche?

Thank You.
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Old 04-21-2014, 04:41 PM   #2
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yes

you'll be a little wider up front than OEM and tad smaller in back.

Unless you track it -- the only thing you'll notice is a little harder to turn at slow speed

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Old 04-22-2014, 09:39 PM   #3
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Bigger contact patch on the ground on the rears to transfer the hp to the road with good traction.

The front are just for steering and at that smaller size they under steer a bit, so for racing you upsize the fronts for better grip when turning and braking.

its typical of rear wheel drive cars to carry more rubber where its needed.
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Old 04-23-2014, 02:51 AM   #4
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Specs from Tirerack, fits 7-9" wheel;
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Old 04-23-2014, 08:30 PM   #5
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Remember that the stock tire widths are 205 front and 255 in the rear. This setup gives the Boxster a good amount of understeer.

By going 245 "square" (same size tires in front and rear), the car will lose most of the inherent understeer and might possibly tend to oversteer. This type of handling can be challenging for some drivers (which is why Porsche built in understeer).

When running a square tire setup in Boxster racing, we have adjustable sway bars and use sway bar adjustments to keep the car balanced (not tending to understeer or oversteer). In your case, a stock Boxster does not have adjustable sway bars so if the car is tail happy, you're just going to have to be fast to catch it.

I'm not saying that the car will become unmanageable; in everyday regular driving you'll probably never notice it.

But... my guess is that you will figure out pretty quickly that the front end has a LOT more grip and if you start exploring just how far that grip goes then you may find the point where the rear loses grip before the front (oversteer). Or even if you're not the type to test out the limits of the front end grip, the same could apply in a situation where you have to make an emergency maneuver.

This may not be an issue but I wanted to let you know what to expect.
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Last edited by thstone; 04-23-2014 at 08:52 PM.
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Old 04-24-2014, 04:48 PM   #6
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Smile

Jinx here again.
I first off want to say a Thank You for all your responses to my
Question.
I have joined PCA and have -- will sign up for a Car Control Clinic.
A question on my original question. I may do a auto cross and
A D E event just for the fun of it. HA I am nervous just talking
About this. But that is my next question.

As you can tell I hate to scrap the tires from the Audi. Cheap I
Guess. Can I use the 245's just on the backs and keep the front
Size stock. I am afraid of the oversteer.
Or should I just scrap the 245's
I am not one to sell things on E-bay ect.

Thanks again for all your help
Jinx
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Last edited by Jinx; 04-24-2014 at 05:23 PM.
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