I run gt2 size pirellis. the rears are 25.5" the fronts are 25.4" I was under the impression that the rears should be a bit LARGER so at a given speed they are rotating a bit slower than the fronts. Seems to me the front differential would kick in when the rears are rotating faster than the front tires ie: when they are slipping, and you need more front traction.

If your rears were smaller, they would always be spinning faster than the fronts. I thought that would increase wear on the front diff...

 

I have a car in my shop thaybhas been running 235/35/19 and 305/30/19 for 40k miles and still working fine. I did tell him to go to 245 front next time he needs.tires though.

having a larger wheel you will have very little power transferred to.the front wheels though.

 

Seems like a 265/35/19 might work out with a 305/30/19 rear ?

 

It might be possible but the amount of work needed to fit a 265/35/19 up front would be very hard. Also would need very stiff coilovers and higher ride height to do so.

 

A 305 rear is 26.3. The 245/35/19 is 25.8. .5 off. Put a little bit higher pressure in the fronts and let the rears wear in a bit. I think this might work.

 

Right, after thinking about it, probably to tall, I was thinking since I ran a 275/35/18 up front with not much trouble. But still it was a shorter tire.

 

I have thought about running pwdrhound's 275/335 setup with AWD... If it burns out the viscous coupling, well I've been interested in going RWD anyway.. just don't want it to introduce weird behaviors on track.. Following this

 

I ran this setup in a Toyo Ra1 before they stopped making the wider sizes, pretty much just threw them on, best the car has ever felt on the track. Can't imagine how good it would be if properly setup for them.

 

Hey Chris,
I'm gonna have your Guard LSD ready to ship by the end of next week. Once you get that installed there's no reason to keep AWD. Sell it before you burn it out. I got $2k for mine 4 years ago. Keep in mind for 275/335s you'll need 9.5/12.5s at least. 9/12s won't cut it. I have some bad *** E88s that would round out the package for you. A good divorce lawyer might be in order at that point...

 

I'm not comfortable selling anything taller than 25.5" tall on a 996, especially up front. The front and rear sizing needs to be the same.

 

Any way you can lobby a tire company to produce an order of 315/25/19's for us? I assume tire rack has some clout at least.

 

As I understand it, with the factory bridgestones the rear tire spins 14 rpm faster than the front making the rear tire smaller. This rear spinning faster allows the viscous clutch to push 5% of the power to the front wheels. Keyboard engineers say that when the front tire is smaller it works opposite and creates reverse drag and premature wear, reasonable conclusion logically but little evidence is offered. Nor can I find accounts of failure attributed to a smaller tire up front.

 

Someone really awesome should put together a simple chart that shows us stock tire sizes for 18" and 19" AWD and RWD and what plus sizes can work for 18" 19" and 20" wheels, with what necessary Wheel Widths, and then tire sponsors and dealers can tell us what they have in stock in most cases what they don't have in stock anymore.

Could call it factory specs and proven aftermarket specs.

.

 

That would be hard given that even in the same size, tires from different manufacturers are not the same.

 

Freddy what do you think about me trying to fit a 235/40/19? 26.4 inch tall. Just two tenths less clearance to the liner than your setup is, but a bit thinner. Is this possible? It would be perfect with the 305's in AWD configuration.