17" vs 15" wheels pros and cons Options

[moggy]

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)
(IMG:http://www.914world.com/bbs2/uploads_offsite/i31.photobucket.com-3285-1440357310.1.jpg)


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

(IMG:http://www.914world.com/bbs2/uploads_offsite/i31.photobucket.com-3285-1440357310.2.jpg)

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?

[moggy]

You yanks and yer V8 conversions (IMG:style_emoticons/default/barf.gif)

When are you gonna learn V8's are only good for boat anchors (IMG:style_emoticons/default/KMA.gif)

(IMG:style_emoticons/default/poke.gif) (IMG:style_emoticons/default/biggrin.gif)

totally agree!! (IMG:style_emoticons/default/beerchug.gif)

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 (IMG:style_emoticons/default/biggrin.gif) 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 (IMG:style_emoticons/default/beerchug.gif) Although I must admit, bad habits die hard, I still have a habit of 4 wheel drifting it around corners on track (IMG:style_emoticons/default/lol-2.gif)

[Cracker]

Huey runs just fine thank you!!

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!

[naro914]

Huey runs just fine thank you!!

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? (IMG:style_emoticons/default/poke.gif)

[naro914]

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 (IMG:style_emoticons/default/biggrin.gif) 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 (IMG:style_emoticons/default/beerchug.gif) Although I must admit, bad habits die hard, I still have a habit of 4 wheel drifting it around corners on track (IMG:style_emoticons/default/lol-2.gif)

Awesome!!
What engine are you running in there?

[Cracker]

Huey runs just fine thank you!!

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? (IMG:style_emoticons/default/poke.gif)

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! (IMG:style_emoticons/default/beerchug.gif)

[naro914]

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! (IMG:style_emoticons/default/beerchug.gif)

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!!

(IMG:style_emoticons/default/beerchug.gif)


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...

[moggy]

What engine are you running in there?

It's a Jake Raby 2315cc beast (IMG:style_emoticons/default/aktion035.gif)

[naro914]

What engine are you running in there?

It's a Jake Raby 2315cc beast (IMG:style_emoticons/default/aktion035.gif)

4 cyl?

[moggy]

What engine are you running in there?

It's a Jake Raby 2315cc beast (IMG:style_emoticons/default/aktion035.gif)

4 cyl?

Oh yeh. Lot's of power and still nice and light and nimble. (IMG:style_emoticons/default/biggrin.gif)

[jmitro]

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

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

[naro914]

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

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"

[mgp4591]

You yanks and yer V8 conversions (IMG:style_emoticons/default/barf.gif)

When are you gonna learn V8's are only good for boat anchors (IMG:style_emoticons/default/KMA.gif)

(IMG:style_emoticons/default/poke.gif) (IMG:style_emoticons/default/biggrin.gif)

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. (IMG:style_emoticons/default/popcorn[1].gif)

[1stworks]

You yanks and yer V8 conversions (IMG:style_emoticons/default/barf.gif)

When are you gonna learn V8's are only good for boat anchors (IMG:style_emoticons/default/KMA.gif)

(IMG:style_emoticons/default/poke.gif) (IMG:style_emoticons/default/biggrin.gif)

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. (IMG:style_emoticons/default/popcorn[1].gif)

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...

(IMG:style_emoticons/default/smilie_pokal.gif)

[Borderline]

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 (IMG:style_emoticons/default/biggrin.gif) FWIW (IMG:style_emoticons/default/biggrin.gif)

[Randal]

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 (IMG:style_emoticons/default/biggrin.gif) FWIW (IMG:style_emoticons/default/biggrin.gif)

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?

[Borderline]

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 (IMG:style_emoticons/default/biggrin.gif) FWIW (IMG:style_emoticons/default/biggrin.gif)

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. (IMG:style_emoticons/default/biggrin.gif) It was a lot of work, but I'm glad i spent the time to do it.

[bulitt]

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

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"

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

(IMG:style_emoticons/default/rolleyes.gif)

[Cracker]

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! (IMG:style_emoticons/default/beerchug.gif)

Tony

[mepstein]

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. (IMG:style_emoticons/default/biggrin.gif)


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

[Cracker]

Yeah, they have a point. Never use more than "three" spacers per wheel... (IMG:style_emoticons/default/rolleyes.gif) (IMG:style_emoticons/default/shades.gif)

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. (IMG:style_emoticons/default/biggrin.gif)


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