Originally Posted by juddz
HDDP, looks nice. I know the stock Crossfire wheel and tire package is pretty heavy on each corner of the car, and excessive unsprung weight is no good on the track. What do you think each wheel / tire weighs?
From what I have seen, you really don't see too many cars racing at the grass roots level with low profile tires. I wonder if this is due to the decrease in "communication" from the tires when cornering at the limits, or because of the weight penalty associated with using larger diameter wheels. Seems to me that 18" front / 19" rear might be good for the street, but a little excessive on the track. What do you think?
I'm Not sure the total weight, my tire shop didn't have a scale and I don't have one at home... I can tell you that the new wheels felt heavier than the OEM by a few pounds, but the new fronts are 8.5" wide and the rears 9.5" wide as opposed to the 7.5/9 OEM combo. The tires are like feathers.
I'll tell you, everything about this car is a major project and sometimes, pain in the ***... I went through 50 different companies trying to find decent performance wheels that would fit the car, that weren't going to cost an arm and leg... And also seemed sturdy enough to take the abuse that I give them on the track... Hell, you should have seen my front OEM wheels when we tried to do a match balance on the Hunter machine. We laughed because they were bent both horizontally and vertically... Probably from a few less than glorious track run-offs into the dirt this year...
I debated alot about this tire, wheel combo... I'm not 100% happy with it either, especially the rears... The 19" wheel causes the biggest issue since Michelin Pilot Sport Cup Competition tires only come with a 30 sidewall in 19" sizes. That side wall is a bit narrow for the track IMO, but the CUP tire is terrific on the track... Competition tires are slim pickin's in the 19" range. I searched high and low for decent tires and even trashed the TOYO S1-R's after I was completely dissatisfied with them with less than two days of track time on them...
I may end-up swapping the rear wheels with 18x10's if this combo doesn't perform right, and put on a 265/40/18 tire in the rear... It's all hit and miss with this car until I get it dialed-in perfectly...
I needed to go a bit wider on the rear wheel / track because I was experiencing some oversteer on my last track day. And since I don't have the availability of many suspension adjustments to compensate, the cheapest way to go was with a bit wider stance by using the spacer and 9.5" wheel
Another thing that concerns me a bit about this new set-up is the 15mm spacer I put on the rears... I might be getting a bit neurotic, but it might just weaken the bond between the wheel and hub, even though they are hub centric. I know it sounds overly cautious, but it introduces another component that could possibly fail with disastrous results or also cause undue stress on the wheel bearings and suspension components in the long run. I also had to use a longer lug bolt which just slides through the spacer with no support from the surrounding hole, instead of actually threading into the spacer and then into the hub. I feel a little less concerned that they are on the rear where there is substantially less load bearing weight, I definitely would not put them on the front...
But your point is well taken... Ideally one would want to go with smaller diameter wheels like 17's with a much thicker sidewall tire so when you hit a rumble strip, the tire absorbs most of the impact and doesn't transfer that energy directly to the wheel, possibly bending it or throwing it out of round... And I think a taller sidewall will give you a bit more flex and disperse the heat build-up in the tire. I also think a smaller diameter wheel would have less chance to flex under heavy torque.
I'm sure there are some other VERY good tire engineering reasons that I am not aware of, which smarter and more experienced people could address... I don't know if you remember our discussion about running 18's on the rear for track use... I think that might be the most effective set-up and there are many more options for Wheels & Tires. Thankfully, I believe ACE and Milano import that same wheel (M708) in a 18x10, but Michelin's closest fit for a comp. tire would be 265/35/18 which only has an additional 5% of sidewall from the ones I have on there now....
Ah Dilemma's... Anyhow, I'm off to Miami for the weekend to shoot the Hot Import Nights / National Custom Car Assn. show... I'll post some stills of these MEGA-BLING cars and hopefully some scantily clad car chicks when I return... See YA !!!