RacerLex

I know many of us look at weight when narrowing down wheel choices but what about tire weight? I don't hear much chatter regarding tire weight and unsprung weight and how it impacts performance.

I'm considering General Exclaim UHP and Kumho ECSTA SPT. The Kumho's had better performance test results by Tire Rack but they weigh about 4-5 lbs more per tire than the Generals. I was going to go with Kumho until I saw the weight differences, now I'm on the fence.

How much of an impact does tire weight play? To my understanding (maybe I'm wrong here), weight matters more as you move further away from the wheel hub. Tires being the furthest from the hub, do they have more impact on unsprung weight than wheels?

Your opinions please.

RacerLex

Is this forum dieing or what? Only 6 views in 15 hours and no reponses.

mitsuguy

iTrader: (2)

it plays a role, but you are always better off picking the tire with better traction than the tire that weighs less...

now, if two tires were identical traction and performance, and one weighed less, I would pick the one that weighed less...

Lexmex

mitsuguy is right

and there would have to be a sizeable weight difference or in revolutions per minute to consider otherwise, but tire manufacturers are very keen as to what the benefits of there tires versus others are and will find ways to improve your advantage.

BTW, mitsuguy will be in Vegas on Sunday for a convention, maybe I will see your SC on the streets.

Blizzy

iTrader: (-1)

You are correct. Rotational inertia, how willing a stopped wheel is to start moving and how unwilling a moving wheel is to stopping, is a function of mass and radius squared. As you move farther away from the center of rotation, weight decisions increase in their importance exponentially when it comes to rotational inertia. Each pound variation in tire weight has a similar effect on rotational inertia as three pounds of wheel weight.

Nevertheless, what is so great about being able to get 0-60mph a tenth of a second faster on dry pavement if you spin the wheels in the rain and are required to take the turns 5mph slower because the sidewall is mushy? Yes, rotational inertia will affect snappiness off the line and braking, but sidewall, tread, and compound construction will probably influence the sum of all of your driving experiences moreso.

I went with the General Exclaim UHP tires on my wheels: 245/35/19 and 275/30/19 in the front and rear respectively. I based my decision largely on rotational inertia stats that I had generated a spreadsheet for to evalute my wheel decision. I intend to continue this philosophy, but I will move up to the Continental ContiSport Contact line in the future as they are still light but better performing tires. The Generals will work well for a year or two. They kept costs down, which was nice. But, ultimately, there are definitely better tires out there, and I intend to purchase them in the future.

RacerLex

Thanks for the replies, what you said makes sense. I should have picked up on this as Tire Rack tested both tires head to head and the Kumho's had faster/better results. Obviously track times for the Generals would have been better if tire weight was the only factor in determining speed - the Kuhmo's coming out on top even with the additional weight disproves this as the only or most important factor. I think I'll be going with the Kumho's.

mitsuguy

iTrader: (2)

damn.... any day but sunday... I'll be in Cali SCUBA diving.... the lex will be parked safe and sound in the garage... any other day and I'd springfor lunch or something...

mitsuguy

iTrader: (2)

I bought Generals at first too - wanted to try them out when they were first released... same size rear, 18" up front... my BFG KDW's are 100 times better in the dry and just as good in the wet... ok, so, not 100x, but they allow about 25% faster cornering speeds with much more predictable slides (when they do lose traction) I actually thought the Generals were awesome until I lowered the car... prior to lowering the car, it felt like it was going to roll over, then when lowered, the roll over part went away and the tires started to want to slip and slide - upgrading to BFG's was a night and day difference... acceleration was not changed at all, as evidenced by 1/4 mile traps (times got about .1 better because of increased traction, but this is negligible, and very well could have been differences in the track, the temp/humidity, or some other weird variance)

Lexmex

Thanks. If you ever get down here let me know, I'll spring for lunch, too

I haven't been in the U.S. in over 2 years.

Brandon@TR

Wow, this thread is impressive. Hopefully other people will sift through the 1000 "How does this wheel look on my car" threads and check this out. It almost makes me want to sticky it... almost.