Wheel size selection, Need some schooling! Options

[KevinP]

I was wondering why someone would want to go to a 17 inch wheel on there 914 from the stock 15 inch.

I now see you have an increase in wheel and tire weight with the increase in size and the chances of have more problems with handling and balance. Are they reducing the difference by going to a low profile tire?

I still see that you have more rotational mass than stock...this i see as a problem or the potiential for.

See if you can edu macate me here............TIA

KP

[914helo]

One reason is that it's hard to find a large selection of tires for 15 inch wheels. The popular trend is larger wheels and the tire manufacturers are following suit.

[drgchapman]

Some random thoughts:

I would say generally, as wheel diameter increases, tire height decreases. You still need to fit into the wheel wells.

I run 205/50/16 tires on my 16"wheels.

The stock tire size for a factory delivered car was 165/80/15. I haven't found that size in many years.

Higher performance tires tend to have a lower and stiffer sidewall height, so to maintain overall tire height you need a larger diameter wheel.

The closer you match the factory tire diameter, the more accurate your speedometer will be as well.

[Cap'n Krusty]

Why? They want their car to resemble a Tonka Toy .................. The Cap'n

[woobn8r]

Although the wheel is larger and the sidewall is shorter, the overall circumference should stay just about the same (if done correctly) The overall mass of the wheel tire assembly changes very little.

True, the percentage of weight at the circumference is slightly increased but this is negligeable in performance...and highly out weighed when you consider the performance benefits of the "modern" tires stiff sidewall and casing designs.

You can accomplish the same weight imbalance and stay with OE size wheels by using a light alloy wheel (i.e.Fuchs) and a cheaper offshore tire choice that weighs more than a performance tire. Runflat tires also will change this ratio as they weigh considerably more than a regular performance tire

That is why each wheel tire package should be researched to see if it suits the consumers needs.

Aesthetics, performance and size availability all influence the decision of which combination to use.

Some people choose to alter their gearing by using shorter or taller tires on the same rim....this may give a greater "hole shot" for an autoX or cheat the dyno on an emissions test.

In the end, unless you are racing I wouldn't worry about the % of mass that is on the circumference of your wheel/tire assembly....it simply is too small a factor to worry about....and if you are racing....there are some lightweight tires available.

[angerosa]

OK - Everyone is touching on the answers but I'll give it to you straight since I'm considering this now too.

1. Appearance - You might like how the different wheel looks. (I bet this is the least common reason for people switching wheels (in the 914 community anyway))

2. Increased speed - If you can make it so your tires have a greater circumference than they do now, you will go faster. One revolution of your tire now covers more distance.

3. Traction - Some people put the GT flares on so that they can actually go with a wider wheel/tire. A wider tire has more rubber touching the ground at any given time so you'll grip more in corners and on starts.

4. GT flares can allow you put a larger circumference tire because there's a little more room in the wheel well. (see #2)

5. Handling - Larger wheels, smaller sidewalls mean when you turn the wheel there is less give in the sidewall and your car will turn quicker giving you more of that go-kart feel. This is huge. A small decrease in sidewall has a huge impact on response (This is the main reason I want different wheels and tires.) If you shrink the sidewalls and don't increase wheels diameter your wheels look funny. A bigger wheel doesn't always weigh more.

6. breaking performance - Larger break rotors and calipers. You need larger diameter wheels to put bigger breaks inside of.

Probably lot more reasons I haven't thought of.

[KevinP]

Thanks guys,

I just put on a set of steel flairs so that I could use the wider tires 15X 7-- 15X8 front & rear. These are 5 lug Fuch. I happened to see there one of our members was switching to 17 inch wheels and I was wondering why? My reason for staying with my 15's -less rotating mass and unsprung weight. If I wanted a "tighter" feel I could go to a low profile tire but this is just a street car I'm not into AX or club racing. Also, there goes my smooth ride while crusing.

I'm still learning about the suspension things and tire set-ups so you guys have been a great help in sheding some light on this.

KP

[G e o r g e]

Thanks guys,

I just put on a set of steel flairs so that I could use the wider tires 15X 7-- 15X8 front & rear. These are 5 lug Fuch.

(IMG:style_emoticons/default/thisthreadisworthlesswithoutpics.gif)

[slackin' at work]

I'd really like to see a 914 with these 17x7s.

(IMG:http://images.thesamba.com/vw/classifieds/pix/1638847.jpg)

not a bad price either:
here they are

[Aaron Cox]

cuz they is heavy (cast) and they can crack (cast)

i think the racers are going to 17's for a better tire size selection in both street and performance/ race rubber.

I believe it is getting hard to find nice street performance tires for anything over a 225 or 245 tire (for those with flares)