You're thinking of things backwards.

Ok, let's imagine the following:

1) You hold ride height constant
2) You increase the diameter of your wheels

What happens to the wheel center?

It's goes "up" from where it was to begin with. As do all the suspension components connected to your hub.

What does this mean?

It means that for a given ride height, your suspension geometry is worse off than it was with the smaller diameter tires.

And if there are other constraints such as fender rub, a larger diameter tire will again require a bump in ride height to achieve the same amount of clearance.

So, you effectively have to increase your ride height to achieve the same geometry you had before AND possibly increase it even more to clear the fenders.

An all-around unless you really need it. The higher speed in 2nd gear can help if you're limited - like in an STI with very short gearing.

 

The taller sidewall will increase the ride height of the car at all 4 corners by about 7mm (0.27"). Lowering the chassis more (with respect to the wheel position) will only create more problems with the stock mac strut geometry in the front. If you're trying to deal with poor geometry in the front then the 40 series is def the way to go, unless of course the height difference really kills top end. You can always bump the rev limiter up to about 8k to gain back some mph.

 

Well you win Mr. Silencer. I bought the Full Race one this afternoon.

 

I have the 45's on my car and they work great. You are over analyzing. Just throw them on and go for it. You don't need to adjust your ride height. The 45's don't change the geometry per se but the car will be 7mm higher. There is enough room in the fender wells that they won't rub either.

 

Hey, you learn from the best, j/k You will not be disappointed. Make sure you get it HPC coated. I'm partial to HPC vs. Swain coatings. Geoff at Full-Race will send it directly there for you. The mid and upper range of this header is where it shines.

Also, get some heat protective sleeves for your O2 wiring and upper radiator hose if you plan on driving it extended periods of time. I have not had a problem, but then again, I rarely drive it on the street.

See you at Midwest Divisionals in Aug.

Dave

 

Heed Dave's advice, Jake. When I saw the pic of that thing I thought it would melt everything within a 5 foot radius.

 

I bought 245/45/17s ages ago when I first needed a set of tires. The 245/40 offerings were not easily found at that time. We now have a decent number of those offerings, though I opted for 245/45 on my next set of RE-01Rs. Why? Well I've been doing a mix of road racing as well as STU and the extra touch of gearing on the 245/45s keeps me out of 3rd gear on a couple corners.

I'm not sure anybody has quantified just how big of a difference the slight height difference accounts for. My tires fill the wheel wells more and I may be up higher than the 245/40 counterpart.

-Jon

 

Trust me I plan on it. I took his advice on the manifold didn't I?

 

Thanks to all you guys' comment. Since I copy everything that davemac does anyway, 245/45 it is; plus extra $70 ain't too bad...

 

Hey Jake,

If you need a source for heat shielding products, DEI has several different lines.

Rick

 

Not EVERYTHING.....I've got more spring rate than you have pain tolerance for you kidneys.

 

Davemac, since I am so much older than you I think I need to go to 50 series tires to protect my old kidneys! Take care and see you at the Farm Show. Danny

 

Dave, Thanks for the advice on the manifold. Fitament is flawless on the piece and I should know tomorrow about power gains. Here's a pic of the final product pre heat protection



This is on the black car since my engine bay isn't NEAR as nice.

 

Dieman,
What air box / air box lid is that?

 

I'm on the phone with him now.. HKS Kansai Service.