rotarenvy

how dose offset effect the 8's handling? say going from the +50 std to a +38 or 40.

on my last car going from a +40 to a +38 the car started to torque steer, tramtrack, and became very nervous over bumps.

the 8 already has a tendancy to be very nervous on rough roads I don't wan't to make it undrivable.

bfulmer

I put a big brake kit on the front of my 8 so I had to use 15mm spacers with the stock wheels. Thus I'm running with +35mm front offset. Had it at the track last weekend and drove it to/from. I did notice an increase in brake pull on crowned pavement but thats about it. Steering seems fine along with rough road (I live in MI so I know).

rotarenvy

sounds good. I'm going to see if I can find a shop that will let me try the +38 before I decide.

Sputnik

When you change the offset, you do change the suspension's geometry. This will affect how the suspension works, and it will throw off the tuning that was done on the suspension. Whether it's enough to offset the reason why you are changing the offset is up to the owner, of course. Alot of people don't notice it, or they don't know what to check to see if there is a difference. The results Rotarenvy observed on his other car were some of those that you can expect.

When the tires stick out farther, the geometry of the suspension changes so that the shocks and springs act like they are stiffer, and more stress is put on those items.

The suspension is designed so that the camber changes when the suspension goes through it's range of travel. The camber settings are set very carefully when you get an alignment on a car like the RX8. Even if you are careful to get the camber set correctly after adding different offset wheels, they won't change at the same rate when the suspension goes through it's range of travel, and it won't work as well.

Just like different offset wheels affect torque steer on a FWD car, it also affects rear wheel traction under acceleration in a RWD car.

And changing offset will affect the feel and feedback of the steering wheel. This is one of the intangible things about a car like an RX8 or Miata that really makes a difference in how connected it feels to the road.

These are minor things, but they do add up, and affect the feel and response of the car. Whether it's enough that you won't bother with changing the offset (for whatever reason), depends on the person.

---jps

rotarenvy

are you sure about this? seems to go against logic. the wheel is further out so it has more leverage on the springs and shocks. so if you move the wheel the spring would feel softer.

the wheel offset shouldn't effect camber. camber and dynamic camber is set by the suspension geometry not the wheels position. ie the mounting surface of the wheel never gets missalined with the change in offset and will follow the same arc regardless of the wheels width or offset.

one interesting point someone on another forum told me long ago; if you change overal wheel diameter you also need a different offset to maintain the origional geometry. but unfortunatly this situation dosn't help me. I see no way +38 will be good for handling

DOMINION

A pair of "off set" tires in the back will cause more under-steer. Thats about it.

rotarenvy

I reckon the front tyres offset would have much more effect on handling. as your changing the scrub radius. the tyres start to move in an arc instead of turning about the centre. this is what effects tram tracking the most, (makes the car follow ruts).

Sputnik

Oops. You're right, I did get that reversed.

But remember, you are affecting the suspension geometry. With a different offset, the same amount of suspension travel results in a different amount of camber change.

---jps