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I am planning on buying new lighter wheels (Jongbloeds) and I wanted to get the group's take on the advantages/disadvantages of 7s and 9s vs 8s and 10s. I have an Elan DP04 which is an FE front with a VanDiemen/Elan back. The FEs run 8s and 10s so that is the stock set up for the car. I very much like the way the car handles but as I am looking at new wheels I thought I'd take a harder look at size question. What is everyone using and why? Any reason not to use the 8s and 10's?
Doug
7's and 9's.
I'd be inclined to look at the mfgr specs for the tires you use and see what rim width they recommend be used with them.
7/9 combo is the definitely the preferred combo with the fast guys. They main reason to go with a more narrow width is for higher straight line speed. You will not feel any significant difference in handling (in my opinion) between 7/9's and 8/10's. Some people use a 6/8 or 7/8 combo also. Hoosiers have 25's and 35's that will fit on all these combos fine (I believe they are 7.5 and 9). The only difference I felt was that the grip on the smaller tires fell off quicker (probably my imagination)
Hoosier recommends the FC rubber on 7 and 9 inch rims.
I preferred the steering lightness of the 6/8 rather than the 8/10. I never did try the 7/9 setup I had... but I've done a lot of dumb things in life.
Hi Doug (That's my boy, I found him wandering around in the rain at Watkins Glen last summer, looking to "Garage Share" as he so pitifully put it... Oh wait - That was ME! ;O)
There was a post a few/several months ago about this subject.
I think Richard Pare chimed in on it.
Basically 8 and 10 are FC wheels that take those tires to support the add'l 200 or so pounds of a FC, which uses that weight to work the tires hard enough to get to the temp range (180*-200*) that will make them work.
Most FB's are too light to make the 22x9 rear work OPTIMALLY (one of the reasons I went to 8" rear tires on my 10" wheels (which is within the range of doable according to Hoosier),but the BEST OPTION for an FB AT MINIMUM WEIGHT is 7 and 9" wheels w/ 20.5x7 front and 22x8 rears.
When running the 22x8 on the 10" rear wheel, the tire is significantly narrower than the wheel, and the tire inflates accordingly, with the sidewall being fairly flat from wheel/rim edge.
When running the 22x8 on the 9" rear wheel, the sidewall pooches out slightly, possibly helping in cornering.
I have run 8" rear and 6" front rims on my RFR for awhile, esp at Rd America for Sprints and R/O's, in the all out quest for the elusive top speed.
The last season I concentrated on making the 8's and 10's (w/ 8" rear tire) work, and the '14 season went pretty well w/ that setup, w/ a car at about 1050 ish post race
I think your car and you at race weight might be pretty close to FC weight, so 8 and 10 wheels w/ 22x9 rears might make temp?
Hope that helps, budrow!
Coop,
That pic looks like one of our drier moments, Mid-Ohio perhaps? I have been on an intense weight reduction plan and expect to be at about 1020 come the new year so I am leaning towards 7s & 9s. That seems to be the prevailing wisdom. As the car was runnning an extra 100lbs of fun last season, I can understand why the 8/10 package was on it.
I just gotta stay off the sweets this holiday season and I'm good to go!
Doug
Quote:
Originally Posted by sprocketmensch
Gee, only another 800 pounds to go! ;)