Front tire issue. Alignment?

[Whiskey11]

Toe in or out on both wheels will effect this, but too much camber positive or negative will effect tread ware. If you don't think so run a couple degrees negative for 10k miles with good toe and tell me you won't have inner edge wear. Especially on a performance car.

I did exactly this on my 2009. -3.0º Camber, zero toe, +7.5º of caster. Tires were 200 TW Extreme Summer Tires, either the first gen Hankook RS3 or the second gen Hankook RS3. Also ran snow tires at the same alignment setting.

Over the 10,000 miles I put on the car with those alignment settings, the car didn't see any more wear on the inside shoulder than it did on the outside or middle. Key is rotating tires and about halfway through flipping them on the rims and swapping the sides they are on. Even with 550lbs/in front springs I still saw accelerated wear on the outside shoulder of the tires from autocrossing and basically none on the inside.

On the other hand, I saw what having toe far out of spec will do to a set of tires in a 300 mile round trip to Iowa for an event on my buddy's Evo IX SE... corded a 75% set of Kuhmo streetable R-Comps.

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[redline727]

I did exactly this on my 2009. -3.0º Camber, zero toe, +7.5º of caster. Tires were 200 TW Extreme Summer Tires, either the first gen Hankook RS3 or the second gen Hankook RS3. Also ran snow tires at the same alignment setting.

Over the 10,000 miles I put on the car with those alignment settings, the car didn't see any more wear on the inside shoulder than it did on the outside or middle. Key is rotating tires and about halfway through flipping them on the rims and swapping the sides they are on. Even with 550lbs/in front springs I still saw accelerated wear on the outside shoulder of the tires from autocrossing and basically none on the inside.

On the other hand, I saw what having toe far out of spec will do to a set of tires in a 300 mile round trip to Iowa for an event on my buddy's Evo IX SE... corded a 75% set of Kuhmo streetable R-Comps.

Rotating them on a 2009 with a solid axle that has no rear camber adjustment will help for sure. Especially if on top of that you are flipping the tire on the wheel (if you're running a non directional tire). That would not be the case on a s550 with staggered fitment unfortunately. Even if you ran a square setup the negative camber dialed in the rear will still wear uneven under heavy throttle. The negative camber is for contact patches in corners. It will not wear even in straight line launches when breaking the tires loose. Most guys taking these cars down the 1320 will dial that negative camber out some. Unlike guys taking it on the road course. But everyone can agree the toe setting can kill a tire much quicker.

 

[Whiskey11]

Rotating them on a 2009 with a solid axle that has no rear camber adjustment will help for sure. Especially if on top of that you are flipping the tire on the wheel (if you're running a non directional tire). That would not be the case on a s550 with staggered fitment unfortunately. Even if you ran a square setup the negative camber dialed in the rear will still wear uneven under heavy throttle. The negative camber is for contact patches in corners. It will not wear even in straight line launches when breaking the tires loose. Most guys taking these cars down the 1320 will dial that negative camber out some. Unlike guys taking it on the road course. But everyone can agree the toe setting can kill a tire much quicker.

Problem is my 2009 had -.20º of toe (yes, toe out) on the rear axle... Thanks Ford.

As for rotating tires, yes, that's the smart thing to do. Either rotating on the wheels and swapping sides (for directional tires) and then adding front to back.

Generally, how my tire rotations went was every 3k the tires went from front to back and back to front (square tire setup with 18x10's and 285's at all four corners). That occurred until the end of the season (about 8k miles) and then I flipped them on the rims and swapped sides so the insides were on the outside. Thing is, that 09 was hard on the outside shoulders even with those alignments... that was front AND back. The rears were almost harder on the shoulders than the fronts were.

Anyway, all of those miles were in Nebraska which has some horrifically straight roads. Most of it highway miles (loooooooong trips).

For the S550, I daily drive at -2.2º out back and -1.9º up front. Zero toe all around. Tires don't look any worse than they did when new... again, outside shoulders getting more wear than the insides. Could use another full degree of negative to help the fronts out, but can't do that in the class I'm in.

You know the real reason why drag racers dial out negative camber in the rear? It's because the suspension geometry forces the tire to go more negative when it compresses, like, you know, on launches. That change in alignment can change grip levels.

Tire wear itself is contingent on how you treat the tires to begin with. I got even wear because they saw frequent rotations. My S550 hasn't been any different. At the end of last year, I took my 275/35/19 RE71R's (200 TW Extreme Summer tires) and flipped them on their rims right before Nationals. I also rotated them around the car. More expensive to do it that way, but it's the price you pay to keep your tires alive the longest. Make no mistake, they aren't wearing because of the alignment, they are wearing because of the LACK of a proper alignment due to highly restrictive class rules. If I had the option to run a square wheel setup, I would specifically so I could rotate the tires. Staggered setups are a horrible idea for even a street car.

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