Sam Strano

You are way, way overthinking this.

Weight matters, not as much as an appropriate tire, appropriate suspension setup and so on. You want as much tire down as you can get, you want as sticky a tire as you can realistically run (use, budget, etc.), you want to control the tire's contact patch as best you can (suspension and alignment).

Sartolw

:-) Kinda thought I was , I need to ask the odd questions sometimes to get a better understanding. Thank you.

JThor

@Sam- I ran RTR last year locally to get my feet wet. I want to stay in F-Street next year. I will be talking to you in the spring about the Koni yellows (and I guess a sway bar). What is the widest width I can go on the wheels in that class? My car (2010) came with 19 x 8.5 (Track Pack I), and Track Pack II cars of that year were 19x9. Also, I understand that 265's are the widest I can go in that class. However, I have seen some comment (Jazzer) that says 265's are too wide for the legal rims. 245-255's would yield better performance. What is your thought? Any input would be really appreciated. Thanks!

Norm Peterson

Technically, any 265-wide tire of autocross interest will be too low of a profile to fit within the Tire & Rim Association tire to wheel fitment guidelines for 8.5" wide wheels. That guideline is mainly for tires used in a wide variety of normal daily driving situations rather than for the very short duration of an autocross run. I am assuming that if you run "out of spec" for autocross that you swap back to a conventionally-fitted wheel and tire setup at the end of the day or very shortly thereafter.

It may come down to a test & tune whether 265's on half an inch out of spec wheels would be better for run times than 255's. At the very least I would expect softer initial turn-in response with 265's, though they might ultimately provide better peak lateral grip.

For peak lateral grip, the optimum camber setting for 265's probably differs from what it would be for 245's or 255's simply because of the greater tire flexibility as installed.




Norm

JThor

Hi Norm,

I think I will be buying a dedicated set of wheels/tires for track/autox. I'm trying to figure out whether a 9" rim would be legal for street class - or do I have to stay with 8.5". From what I've seen the Track Pack cars of 2010 had 9" rims. There's a 2013 with stock 9" rims in F-street locally. So, can I run 9"?

Even with a 9" rim would it make more sense to go 255? You raise a good point about the camber.

Norm Peterson

I think the first hurdle to get past is whether that 9" rim was a stand-alone option for that year Mustang or if it was part of the Track Pack package, in which case you'd have to put the whole Track Pack package together. Sam would know about this better than me, as I haven't even been receiving Fastrack emails to stay up to date on the whole Stock/Street mess.


What I have consistently seen in the previous Stock category with R-comps is that most people still favor more tire at whatever cost in precision or response comes with that . . . if you're running hard enough you're sliding around a bit anyway. It's in the classes where more extensive modifications are allowed - STU, SP, and up - and where the wheel width rules are pretty lenient that you're more apt to see relatively wider wheels for any given tire size.




Norm

JThor

It probably won't be a big problem to upgrade to Track Pack II specs. I think I have to do springs, front and rear LCA's, and reprogram the AdvanceTrack. About $700-900 total. There were upgraded shocks and sta bars, but those were part of my upgrade plan anyway (and they are still free in Street). Everything else was included in my Track Pack I package. They would be desirable upgrades anyway, except maybe the AdvanceTrack. I usually turn off the nannies in performance situations.

I plan to do the upgrades late winter/ early spring. So, Sam will get some business from me.

Sam Strano

Don't waste your money "upgrading" to Ford Dampers.. and one bar is legal to change in street under the rules, and we'd want to not use a Ford bar on the rear, but the 8419 adjustable rear I make instead. And remember you have a '10 so that's going to be a little different parts wise than the later "track pack" and Brembo cars. Have to make sure you get the correct parts for a 2010 model. Since dampers and one bar are free, we'll put Koni's and the adjustable rear bar on it.

Sam Strano

You can only run the rim width and offset (within 1/4" on the offset) that the car could have come with. That's always been the rule, the only change now is you can go up or down 1" from the stock diameter. But you can't run wider or different offsets. Frankly it's stupid and more complicated for people. I *think* your car came with 8.5's which means you can't run 9's. '11+ Brembo cars had 19x9's, but only those can run a 9" wheel... if the car came with 8.5's or 8's as the later base cars did that's the width you have to run unless you update the car to Brembo specs. Again, this is an example as you have a 2010 so the Brembo wheels are not even in play.

JThor

Didn't the 2010 Track Pack II cars come with 9" wheels - or did they put the 255/40-19's on the 8.5? My car (Track Pack I) came with an 8.5 x 19 optional wheel, but I had 245/45-19 tires. Here's an article from Car and Driver going through the 2010 Track Pack specs. http://www.caranddriver.com/reviews/...trumented-test Unfortunately, they didn't specify the width of the wheel. BTW, Track Pack I was also known as the 3.73 axle package that year.

Aside from shocks and sway bars, I think the only items I would have to upgrade to make it a Track Pack II car are the LCA's, springs, and maybe the AdvanceTrac programming (the AdvanceTrac may be the same between the Track Pack I and II cars). Everything else was included in the Track Pack I.

I plan to upgrade to the Koni Yellows (from you) this spring. I will also look for your advice on the sway bars. Thanks!