Tire Size and Gearing

[b4z]

The Marauder has very tall rear tires. 28.6" These rear tires are tall enough to negate the 3.55 axle ratio.
If you compared a GM with 225/60R-16 tires and a 3.27 axle to the Marauder you will find that the overall gearing is almost identical.
About a 3.30 for the Marauder.
A set of 3.70's or 3.90's would increase cruising rpms only slightly and
help get it off the line.

If the rear tire were changed to a 245/50R-18 then the height would drop to 27.6". A 255/50R-18 would be 28" tall. Both of these would help to lower the effective rear axle ratio.

I wonder if a 255/50 tire would rub the wheelwells?

[Logan]

It's REALLY tight in the back end... Though the factory usually tries to leave a LITTLE bit of space to play with... I'd have to go measure it...

Anyone else know for sure?

[b4z]

Logan,

Is it me or do you think the rake might be a little too pronounced?
The 50 series tire would get it down about .3".
The difference in height between the front and rear tires is 1.35"!!
Which means the rear is sitting up about .675 inches.

It looks a little too seventies to me.

I think i would put the 50 series tires on the rear.

Do you think the higher rear end might cause the car to roll oversteer?

The car I saw in Hendersonville, NC was not driveable because the factory had put a 235/50R18 tire on the right rear.
The factory was shipping down a tire to replace it.
This particular dealer wanted MSRP.

[Jim]

I've been pondering just such a set of changes; shorter rear tires, and a lowering of the rear end.

The lowering would be simple, and reversable, by adjusting the air suspension sensors.

The rear tires are a tight fit to the fender wells (hence the factory rolled lips)...

Here's what I've pondered, if I get around to taking my car to the track: swap the front and rear tires. The improvement in gear ratio would probably be quite noticeable?

-Jim

[b4z]

Jim,

I think the improvement would be slight.
If you did a 255/50R-18 it would be a little over 2% difference from the stock tire height.
The 3.55 gear would feel like a 3.62 gear.

My thought about going up to a 255 and down to a 50 series tire is that
since the sidewall is more vertical and less round you would not have
that much of a difference that could cause interference in the wheelwells.
Since the tire would be shorter, it would be less likely to rub.

Perhaps a wheel with slightly less backspacing combined with a slightly wider tire but shorter in height would be the hot ticket.

Maybe one of the car mags will play around with this in the near future.

[b4z]

I would do the lowering completely with the shorter tire to leave some room in the wheelwell for a 255.

[Jim]

Interesting.

I have to think that a 235 50 in the rear (the current front tire) would make a reasonable difference?

The rears are 1.3" taller than the fronts, as it stands; a roughly 5% circumference difference.

Honestly, this thing doesn't yet merit an even wider tire in the rear...

Of course, change out the rear gears, add a chip-n-filter, and then I think I'd have the rear wheels widened and go to something like a 265/50 18, just for fun.

-Jim

[b4z]

since I am having so much fun with this gearing thing I thought i would compare it to a vehicle with a 4.10 rearend.
The Trailblazer/Envoy/Bravada offers a 4.10 gear from the factory.
I plugged in the tire height to compare it to the Marauder and found that a marauder with a 3.90 gear would be turning slightly less rpms than the Trailblazer.
So there won't ba a huge mileage penalty with the 3.90s. Heck you could proabalby put the 4.10s in there and be okay.