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Speed3's can and should go as wide as possible up front with your heavy front ends. Do the rules prevent your from going Mack-stance (285/245)? Gearing may be an issue depending on the track but our heavy front ends demand tire. The more the merrier!
 

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Yep...but you have to replace the motor mount on the passenger side every 4-6 months, the car won't rev past 4000 rpm (on the 2011+ cars for sure) when launching, on a power course it can't keep up with Andres' Mazda2 even...and gearing? GPS verified 54mph in 2nd gear at redline on the 23" tall tires. So I did a LOT of 2-3-2-3-2 all year. Nearly every national course I had to shift at least once. :)

Reliability was a big factor in not running a mini again. And the cost to prep is more than the 3 as well. :)

I've always been a Mazda guy anyway. :)

Oh the irony! Hendricks, are you seeing this!?
 

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Discussion Starter #24
Speed3's can and should go as wide as possible up front with your heavy front ends. Do the rules prevent your from going Mack-stance (285/245)? Gearing may be an issue depending on the track but our heavy front ends demand tire. The more the merrier!
Rules limit to 265 width tire and 9" wheel. If money were no object I'd run 265/35/18 front and 235/45/17 rear. I might end up at this setup, but I'm going to try the 255 square setup. It's way cheaper, and being able to rotate them will save a lot of tread life. Especially since I'm considering daily driving them like last year. If I run out of gearing often I might reconsider sooner.
 

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What do you think the "race weight" will be with full STX prep?

The set-up Jeff Hurst used at Nationals when he won STX in his RX8 seems to be gaining popularity. 235/40ZR17 Toyo R1R's on 17x9 wheels. A local STX BRZ tried it, and had great results, but it's in the 2700 pound range. I'm guessing the Speed3 is just a little too heavy to get away with that set-up though. Not sure if the smaller diameter would help or hurt the gearing.
 

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Rules limit to 265 width tire and 9" wheel. If money were no object I'd run 265/35/18 front and 235/45/17 rear. I might end up at this setup, but I'm going to try the 255 square setup. It's way cheaper, and being able to rotate them will save a lot of tread life. Especially since I'm considering daily driving them like last year. If I run out of gearing often I might reconsider sooner.
Gotcha. Having run a 255 square setup for a while now, IMO it works but surely it's not the best setup out there. I don't think my rear tires heat up until near the end of a 10-minute session, while my fronts have been hot for at least half of it. That sometimes results in bad behavior in the second half of the session. For AutoX that could make your handling balance tricky to manage between runs and you may find yourself wishing for the 265/235 stagger.
 

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Discussion Starter #27
Or there is the possibility of running a 255/225 stagger. I've always run square setups on all autocross cars I've ever put together, or driven competitively. You can tune balance easy enough with spring rate/anti roll bar changes.

Heat is not a huge issue in autocross as far as front-to-rear differential is concerned. Having a narrower rear end would be nice and that is definitely something worth looking in to.

After doing some more tire circumference calculations it looks like the 265/35/18s nets you an extra .6 mph over the 255/40/17s at peak autocross speeds. Not worth it for the additional money for wheels, plus the $100 extra per tire over 17s on the high wear axle! I'll just learn to drive better for that much money.
 

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I felt the 255's were much quicker in acceleration (especially coming out of slower corners) and much responsive for turn in when we took the MS3 for a ProSolo in 2012? The maximum grip was not as good as the 265's but this car wasn't designed to do well in long sweeper anyway so the slight grip advantage of the 265's weren't quite worth it. Plus we had to raise the car significantly for clearance purposes.
 

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I've got a pair of almost new 265/35-18 Z1 Star Specs my dad wants to get rid of :) Interested?
 
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