Decided to weigh my new V700's; 245/45/16. I put a pair of them on an electronic scale for accuracy and they are heavier than I thought. 26 pounds each! If the stock wheel weighs 16 pounds (that right?) than that gives me 42 pounds at each corner.

Hmmmm, that last pound or two of wheel weight doesn't seem so important now. The wheel would have to be four pounds lighter just to get a 10% decrease in unsprung weight on each corner. Super-mega light wheels are $$$; I think my money will be much better spent on suspension.

Anybody weighed any other tires? I know the Hoosier is supposed to be lighter as well as Kumho's new Ecsta competition tire.

 

That's about what i got when i weighed my OEM + V700s. The Hoosiers are much lighter as they have nylon belts instead of steel. Haven't heard much of the Ecsta V700....lotsa mixed reviews. Greasy when full tread (needs to be shaved). Greasy when up to temp. Takes a long time to get up to temp. etc. Think I'll stick w/ Victoracers for another season....unless they make A3S03 in 255/40-17.

BTW, rotational inertia is like 3x that of the static unsprung weight. So it'll save up to 30%...not bad.

 

Remember, weight at the outside of a rotating body (tire) has (by far) the biggest effect on rotational inertia. Makes big bucks for ultrulight wheels with heavy tires seem even less appealing. I think the Hosier comes in that size in an R3S03, I would bet the weight savings might be worth the compound trade off (maybe I'm thinking of 255/45-17).

 

Wheel weight has the same effect on unsprung weight as tire weight does. Low unsprung weight improves tire contact and even ride.

Tire weight is much more important for rotational inertia because of the larger diameter. Tire diameter is also quite important for rotational inertia.

Every pound counts, so I think the desire to seek light wheels is still quite valid. Especially when you are using larger sizes, getting light wheels and tires is quite important. Toyo and Bridgestone generally make light street tires, and Hoosier is far and away the leader in weight for track tires.

-Max

 

Yep, Yep, I agree with MAX!

ML
MDC
www.autosportoutfitters.com/mdc/

 

Hoosier A3S03 245/45-16 on stock rims = 34 lbs.

 

Weighed my road wheel/tire setup today.

255/40-17 Yokohama AVS Intermediate inflated to 32 psi cold mounted on a 9 x 17 SSR Integral A2s (45 mm offset)--46 lbs

Hoosier sports car racing radials don't come in 255/40-17s. You'll have to settle for 245/45-17 OR 245/40-17 OR 275/40-17.

FWIW the Kumho 255/40-17 V700 is about as wide as typical Hoosier 275/40-17 R3S03...

 

My 18x10" CCWs with new 285/30-18 BFG R1A tires weighed 46.4 lbs. After about five track days, they now weigh 45.8 lbs each.

-Max

 

That's light for 11 inches of tire contact patch!!

 

I now have a brand new set of Hoosiers 225/50/16 to go with my Victoracers, 245/45/16. Haven't weighed the Hoosiers yet, but I can tell you that with all four of them stacked up they are a couple inches wider than the Kumhos even though the Hoosier is 225 and the Kumho is 245.

There's the difference in manufacturer sizes everyone always tells me about.

Happiness is two sets of new race tires in the garage

 

"The wheel would have to be four pounds lighter just to get a 10% decrease in unsprung weight on each corner"

More than 4 lbs lighter, as the brake disc, caliper, spindle, lower half of strut ***'y, all are included in unsprung total. But, the lower the better for grip on a rough track, ride quality. Effect is less on ET.

"BTW, rotational inertia is like 3x that of the static unsprung weight. So it'll save up to 30%...not bad."

Regarding strait line acceleration, same overall diameter tire, every 1.0 lb less wheel/tire weight is about same as 1.7 lb less total car weight.

If the l.0 lb was all magically removed from the tire outside diameter, for highest possible inertial effect, then the effect on acceleration is 2.0 lbs total weight reduction.

so, for 4 lbs saved per wheel, 3000 lb original total weight with driver, 27.2 lb typical effective reduction, or .9 % . The max effect possible (2 for 1, getting 32 lbs) is only 1.07% less total effective car weight.