Got Vette?

Does anyone know about performance gains/losses with changing your rims sizes, weight..etc Top speed? low end?


one more question.. is there a good reason why GM put a stagger fit on the c6. sorry if i spelled it wrong. what would the affect be to put all four wheels the same size

Weedo

Not sure what you mean... the C5 is a stagger also. 17" in the front, 18" in the back.

Got Vette?

i mean why does gm put a stagger fit, is there a technical reason? I also wanted to know if anyone knows the gains/losses with changing rim sizes or putting same size all around?

LTC Z06

A larger diameter rear wheel has a larger foot print, more traction, and then you save money because the front doesn't need the larger wheel/tire combo.

Lazerwolfe

Maybe to help with the stance?

Redshift

I think it has mostly to do with looks. You could get the same performance (or even better performance) by putting the same diameter wheels front and back. It just happens to look better this way. I believe the book All Corvettes are Red answers this question on wheel sizing front to rear, and I suspect the C6 answer is the same.

CPTZ06, I'd love to hear about your experiences at the Nurburgring with your Z06. We just got back from a 3-day school there!

LTC Z06

Guys, I've read this in numerous places, GM to save money put the bigger wheel on back for more traction and a smaller one up front to save money. Since the tires due to width couldn't be rotated anyway it made sense. The stance is not it the overall diameter of the wheels and tires is about the same.

Red I always wanted to take that 3 day school, have you posted in raodracing yet?

Redshift

CPT, not yet. I just finished digitizing an in-car video that we took but I'm trying to find a good compromise between file size and quality. I have a big version that is about 200MB, but most people won't want to spend that much time downloading it.

mikeivan

I thought the smaller front wheels reduced drag, I read that somewhere.

LTC Z06

Aerodynamic drag from wheels is a function of their width not diameter.

Scissors

Dave Hill said the sizes were made different purely for aesthetic reasons.

You can get the same footprint with the 1-inch-smaller wheel just by adjusting other aspects of the wheel/tire measurements.

L76

Why do the C5R race cars have staggered sizes? Formula One? NASCAR?

jschindler

Many high performance cars (like all Porsches, Ferraris etc) have much smaller tires on front than back. Much of the reason has to do with the turning characteristics of the car. It effects the responsiveness of the steering. As stated elsewhere on this thread, the bigger rears are to handle the traction needed for high horsepower cars.

Stagger on race cars typically has to do with the same issue on road race courses. On NASCAR the stagger is from one side to the other because they only turn in one direction.

AP

I have heard the drag thing too...

RocketSled

You guys have missed the single biggest reason for smaller/narrower front tires: Trough walk.

Having a Vette with 285x40r17's all the way around, I can attest to the car wanting to follow every single road imperfection that's even remotely close to the direction of travel.

So, there's an aesthetic aspect, but there's a day-to-day comfort and livability one too.

LTC Z06

Alignment has more to do with that than width, many coupe drivers that traded for a Z06 complain about that, we tell them to get a coupe alignment, it helps a lot.

jschindler

I have 275/40-17s on the front of mine and it feels no different than the stock sizes. I know this can be a factor, but on my car it's not noticable.

RocketSled

Hmmph, must be that auto-cross alignment I've got then.

Tokae

in regards to the euro cars that you mentioned with narrower front wheels... they are like that because most of the weight is located areound the rear of the car due to their mid/rear engine setup

SWCDuke

The different front/rear tire load capacity, which is evident in the differential sizes, is there to balance the handling and most high powered cars, regardless of engine location have higher load capacity rear tires. Viper and Maranello are additional examples.

In engineering terms, specific front and rear tire characteristics are selected to achieve an optimum tradeoff between lateral acceleration response time and yaw velocity damping.

Handling characteristics are evaluated using some very esoteric mathematics and terminology, and most of what you read on the internet about handling is crude and often inaccurate because very few understand the current state-of-the-art in handling analysis and design.

Duke