I don't seem to see many 914 circuit racers with 17" wheels on. Everyone seems to stick to 15". Is there a reason for this? I'm less bothered about the looks of 17" vs 15", I'm more interested in this from a performance perspective. Who out there has tried both wheel sizes? what size did you decide on, and why?

I personally have 15" (Cookie cutters 7" wide all around)



and 17" (Cup1 7"front 9"back)



At the moment, I'm forced to use the 17" on tracks where I need the top speed, due to my low ratio gearbox (a hangup from when it was a rally car). The 17" wheels have a 26" overall diameter. Whereas the 15" wheels are used on slower, twisty tracks.

There is a huge weight difference between the wheels (including tyres) of 32kg (70.5lbs) total, which is an obvious benefit to sticking to the 15 "cookie cutters. But weight can't be the only reason why you circuit racers stick with the 15", so what are your reasons?

I ran Hoosier R35 Canti on Fuch !5 X 8s up front. The wheel & tire assy each weighed in at 32 lbs. The rears were no longer made 10 X 16 wheels with R35 22.5 X 10 Hosier slicks in back... both were bias plys...the weights were the same. The weight savings alone are a very good argument, IMO. At two sets per season even the bias plys were costly.

It's been a while since I looked at the Hoosier catalog but there were a wide array of 15 & 16 inch race tires available.....much more so than 17 & 18 and those were much more pricy.

Bigger diameter wheels give you a slightly larger contact patch but also a lot more weight. Modern cars do it for the brakes. Big rotors for overweight cars

You can fit 15s so you don't have overly large brakes. (Unnecessary on Any 914 anyways).

Factory's calibrate suspensions on modern cars to account for this weight.
Old cars need different spring rates (shocks/and more) to take the pounding this kind of weight puts on components.

You can find a lot more tire sizes (Especially wider) in the 17" variety. Most modern performance cars are in this range.

I've been on 17" twists but was thinking about going to 15" merely for the weight and smaller diameter options. An old racer told me that I would be going backwards if I did that and that everybody generally needs to go to something bigger than 15" because of the fitment of bigger brakes. I have a 3.6 and a 915 so I'm probably heavier than most guys and the speeds I'm running I think bigger brakes are a must. I did pick up some 15" Wheels and they don't clear my rotars. Consequently I'm back to looking for some lighter 17's and even considering some 18's but I'm not certain they will fit??? Can someone chime in on 18" fitment? Thanks!

Let me throw in there too that 17 and 18 inch wheels, even when run with low profile tires, tend to be larger in diameter than 15s. This doesn't work well on older cars due to limitations in how much you can lower the suspension and also inner and outer fender clearance. I've seen 914s and older 911s running larger diameter wheels and having to run the car at artifically high ride height. Seems like a bad plan to me unless you just like the look of the larger wheels and prioritize that over performance.

I run 16" wheels with slicks on my 914 racecar. I've already made changes in the suspension and bodywork to run the car very low with the 16s. I've contemplated running 18s, but I'd have to make more changes to the front bodywork and I'm not sure the 18s would give me a significant performance advantage.

My 914 weighed in at 1700 lbs. with a 2.7L. It was an AXer. I did consider going to SMALLER rotors rather than the early 911 set up in place. But it was not worth the hassle and need ballast to make XP weight. The brakes were much under worked. Stock 911 street pads & rotors. I ran it in a DE at about 2100 lbs and they got to stinkin' a bit. but worked fine.

The lower of smaller (height) is good for CG. I don't know what you use your 914 for.

Big wheels and brakes do look cool to be sure, but they are definitely heavier as well. Personally I don't think 300 hp (which is more than even most heavily modded 914s make) justifies 17 or 18" wheels or huge brakes. Later model cars are a lot heavier and have more horsepower, and need them to go fast. The vast majority of 914s don't, and will probably be faster without the extra weight.

we run 16" on both Huey and Papa Smurf. 993 rear calipers up front work/fit perfect.

From a functional perspective, a lower profile tire/wheel combo will provide a different (read "better" to most) experience. Of course, this also has allot to do with factors other than simply the wheels diameter. Tires, suspension, sway bar(s), springs, etc obviously all play a role...

Visually? This is purely subjective...I can make a case either way. Looking "old" versus a slightly more-modern look could be debated ad-nauseam like that stupid 904 thread forever (yes, I un-subscribed)!!!

Here is my steel flared track car on 17's - I can't say it looks bad but I'm sure someone probably thinks it does - I don't care. I actually prefer the look but more importantly - they offer better performance (my opinion only). They "work better" than a 15" wheel and with allot more support/supply of tires and sizes from the manufactures.

Regarding the "weight" issue...how fast do you want to go and how much can you spend? The answer to that question will lead you down several different paths. Light (and larger) wheels are available - $$$$! Not everyone needs larger brakes, as noted in this thread, so budget, HP, intended environment (Race track vs AX, etc.) will go along ways in influencing what the correct decision will be for you.

All the best!

One point to note about weight in the case of wheels and brakes is that in going larger, you pay more for the additional weight so when using unnecessarily large, you can wind up paying more for no improvement or even a decrease in performance. It is not a simple equation though, since as you note the selection of street and DOT race tires is better in the larger wheel sizes. And of course there are other factors like looks that are obviously a personal choice.

I have Boxster brakes on my car and they do fit under the 15" cookie cutter wheels i run.

For the track, i use 10" wide GoodYear R250 slicks with those wheels.

So it seems the only real reason to go for 17" wheels is to be able to fit bigger brakes under there or for maybe better tyre options.

That's pretty much what I thought, but it's always worth a second opinion.

I would have stuck with my 15" Cookie Cutters if it wasn't for the fact that I have a very low ratio box as a hangover from my rally days (e.g. 5th gear is my original 4th). I'm going to put up with the big 17" for a while. At least until I've saved up enough to afford a gearbox rebuild and put some sensible ratios back in the box for circuit racing.

For info here's some weight comparisons of my wheels/tyres:

15" Cookie Cutters (7" wide) with Hankook Ventus 200/580 tyres = 16kg (35.3lb) each

17" Cup1 (7" wide) with Yokohama AD08R 205/50 tyres = 22kg (48.5lb) each
17" Cup1 (9" wide) with Yokohama AD08R 245/45 tyres = 26kg (57.3lb) each

"So it seems the only real reason to go for 17" wheels is to be able to fit bigger brakes under there or for maybe better tyre options."

There are probably some performance increases to larger wheels when used in certain situations. Probably one reason why wheels got bigger in the first place.

But a 914 suspension is very dated and might not work as well with big wheels as a newer car.

You wrote:
15" Cookie Cutters (7" wide) with Hankook Ventus 200/580 tyres = 16kg (35.3lb) each
17" Cup1 (7" wide) with Yokohama AD08R 205/50 tyres = 22kg (48.5lb) each
17" Cup1 (9" wide) with Yokohama AD08R 245/45 tyres = 26kg (57.3lb) each

I wrote:
Those CUP wheels are the worst...kind of the equivolent of lead wheels. I had a second set for my Boxster S race car - the rains were on them and were rarely used. I understand that's what you "have" but that's not a realistic baseline for someone else choosing their tire/wheel package (from the beginning).

PS: I don't have larger wheels for the brakes...its the handing and tire choices.

Tony

Huey has 16x8 Fuchs for street wheels, 16x8 phone dials for track wheels. Both are very light, and the phone dials are VERY cheap.

Personally, I think 16's are the biggest that look right on a 914.


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then again, some people put V8's in 914's so what do I know...

Some of us actually want cars (with engines) that run...more than four laps!

...you asked for it!

Huey runs just fine thank you!!

You yanks and yer V8 conversions

When are you gonna learn V8's are only good for boat anchors

totally agree!!

both of mine have PORSCHE 3.2 engines in them...one actually works all the time!


BTW moggy...is that you rallying your 914 in your avatar??

Yep, that's me Bob. I competed in the British Historic Rally Championship for 7 years in it, retiring it 2 years ago. I felt I had punished it enough I was never as happy as going sideways, on opposite lock, looking straight ahead out of the side window. 2 classic examples of that are below:

https://www.youtube.com/watch?v=BUKOXHeH1bc

https://www.youtube.com/watch?v=-SeD-J6JqYY

I'm converting it to a circuit racer now. Retiring it (and me) out to some smoother surfaces Although I must admit, bad habits die hard, I still have a habit of 4 wheel drifting it around corners on track

I was a product of the 70's and therefore heavily influenced
by this ad campaign...

Link: I could have had a Flat-6 commercial!

so you're saying your car is a veggie mobile?

Awesome!!
What engine are you running in there?

All in fun of course but lets not delve into another "motor" debate...it is senseless. Have a good day Bob - I'm going to have a v-8 tomato drink!

Absolutely all in fun!! Isn't that what this hobby is supposed to be all about??

You are correct, senseless... One of these days I need to see this beast you've built. Based on what we've talked about, it's sounds pretty bad-ass!!




Back on topic....moggy I would highly recommend looking at 16's. The geometry works pretty well and the gearing ends up nice: Meaning you can lower the car just fine and not mess up the rear suspension geometry much, but have that extra bit of wheel diameter to help extend speed and gear ratios.

Personal preference, but I've just always thought 17" or more looked like too much wheel on a 914...

It's a Jake Raby 2315cc beast

4 cyl?

Oh yeh. Lot's of power and still nice and light and nimble.

looks like the higher offset phone dials. 53mm? Do you use spacers with the phone dials?

They are 1987 944 turbo wheels - I'll check spacing size today as I need to put them on for an autocrosss tomorrow. yes, we use spacers on the rear for both the phone dials and Fuchs..something like 1"

Not baggin' on anyones engine choices but isn't it fact that a big P six weighs as much if not more than an LS1? I've never personally looked it up- this is just from what I've read on threads here... Probably doesn't include the cooling system but then that just balances the car out with a little weight on the front end.

I just finished ls1/boxster S 6 speed.My car came in at 2300lbs.
All metal narrow body,full stiffening kit and not much else.

I can't express how fun it is to drive...

For AX I really like my 13" wheels. The smaller diameter drops the car 1.5" so the suspension can run closer to design points. I dropped about 80# of unsprung wt between smaller rotors, Willwood calipers, 13" wheels and tires! Also, I'm finding that 13" tires are about $100 cheaper per tire FWIW

Bill is right.

Regardless of the venue you/re running, unsprung weight is critical. The lighter the wheel, tire and brake combinations you create the better. Also don't
forget tire height, i.e., why would you be running (15") 23" high slicks in the front, when 21.5" height tires are available?

The Avons that are on the car right now are 20" in diameter. I really like that I can put 15" street tires on the car for driving on the street and it raises the car up 1.5" for extra clearance and then the slicks lower it down for competition. Also the shorter tire allows me to start the AX run in 2nd gear helping to save the tranny. It was a lot of work, but I'm glad i spent the time to do it.

Good point. 17's + Spacers (or any wheel with spacers)= much more weight than properly offset 17's

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Assuming none of us are the second coming of Brian Redman...you're generally splitting hairs on the added un-sprung weight. Yes, the combo of spacers, larger wheels and tires is obviously heavier but hardly so that (in most cases) it changes significant results. This doesn't even account for the added benefit of a better performing wheel/tire combination. Install what is aesthetically pleasing to you and the impact of "that" choice (faster or slower) will be hard to distinguish for even the (average) advanced driver. Cheers!

Tony

My coworkers claim that too many spacers place more wear on the bearings. They mostly build 911's. Not sure if that's true on our light cars but it is another thing to think or obsess about.


I'm probably going to use cookies with 2" spacers on my Suby build just to annoy them.

Yeah, they have a point. Never use more than "three" spacers per wheel...

Tony

FYI, I have 2" spacers on the back of Papa Smurf...none on the front.
Huey has 1" spacers on rear, none on front...

Never had bearing or axle issues (LOTS of other issues, but none related to wheel/bearing/axle stuff)


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