'73 with rebuilt 1.7 that is assumed to be more or less stock, even if it is warmed over a tad bit it is still not a powerhouse of a power plant


I have a choice of rims for final build....

16x7 using one inch spacers (that more or less makes the wheel combo set heavier)
(currently has 205's)
or

15x5.5, no spacer.
(currently has 195's)

Both sets need brand new tires and since not a race car and it might see one auto-x a year no need for super sticky tires. So lets say both would get same brand middle of the road tire.

I'm thinking the smaller setup would be better right off the bat due to be a lighter combo however would the lateral grip be better with the wider setup?

Being a street car and being the responsible person I am, I'd venture to say that I wouldn't ever reach the point of needing the extra lateral grip if that is a something that the one combo would excel at.

all things being equal, yes the wider rim would give you better grip, even with same size tire since less sidewall roll.

but there are many variables that go into your choice of narrow vs wide, and I'd say that tire grip is probably one of the least for a street car that never sees the limits of grip

it probably actually makes a difference after youve spent about 100 hours at drivers schools.

What engine? John Forbes frequently mentions "over-tiring" these cars, if there isn't enough engine to make up for it.

I think the overall footprint would be almost the same area (sq inches--the 195's footprint would be a tad longer, 205s a tad wider) so probably not much difference if they are the same tread, compound, etc. Biggest difference is that the 205s on a 16x7 wheel would have a shorter--and straighter--sidewall, so probably a sharper turn-in when compared to 195 on a 15x5.5. Ride quality on the 205s would likely also be a little stiffer than with the 195s . . . .

A short discussion of the subject at Tire Rack's site:
http://www.tirerack.com/tires/tiretech/tec...e.jsp?techid=10

And here's a more in-depth discussion if/when you have the time:
http://www.performancesimulations.com/wp/f...-tire-pressure/

FWIW, I'm kind of facing the same question--I have all the stuff to do a 5-lug conversion, as well as a set of 5 OEM Pedrinis. FWIW, I'm leaning towards refinishing the Pedrinis with 196/65HR15 tires just to keep more of a stock look (at least for today).

As near as I can tell, for a DD car biggest down-side to the 15x5.5 wheels would be the lack of selection when it comes to tires.

Hope this helps!

Grab some sticky tires and I think itll still handle better than 90% of the cars on the road... direction changes should be better with narrow tires

Another factor is un-sprung weight.

Unless your car is flared and has a significant power increase, I'd stick with the smaller rims and tires. You won't notice any real difference on the street and the car will be lighter and easier to steer with the original size.

My conversion car with 7" and 8" rims steers much heavier than my stock -6, and can be quite a handful at low speeds while parking.

Is wider better. Sometimes it can be fun to get a little loose.

Just before you loose the coefficient of traction...

Couldn't have said it better. But then, that's where the real driving comes in. Narrow or wide, its all a personal preferences.

I think I am seeing the downside of a tall sidewall right now with 195x65x15 but maybe my rear sway bar is playing a big role. may disconnect it to see if there is any improvement. still need to get an alignment too.

that said, i'd say some lower profile tires is important, thus a taller wheel 16" or 17" may be the solution for me.

I couldn't find sticky tires in stock diameter 15". Just the econobox stuff. So the 16s might be worth it just to get some decent sports car tires.

7s are a tight fit in back, spacers would be pretty thin, depending on camber.

My camber is near 0 to get the 225/50-16 7" boxsters 5/16" spacers to not rub the inside. And 215/60-15 on 15x7 944 cookies rub the rolled fender.

You might need to mount a used (cheap) tire and trial fit it.

Wider low profile tires look cooler.

Narrow tires, less footprint, will give you more of a chance to tune that 1.7 to attain 40 mpg.....or really damn close to it, with tall tires.


But, for me, I would go with the 7 inch 16s
Look at Ricks car, he has those wheels, just a nice look.

Also, tire cost and spacer cost should help with the decision.

Sad to admit that I have both setups already... 16x7 Phonedials with spacers on car and 15x5.5 rims with 195/60's sitting under my workbench

16,s

I went with 205/65 x 15s and I should have just gone with 195/65. The tires are just a tad TOO big.

I did notice that right after the full 911 front end surgery, with all new ball joints, turbo tie rods, etc., the steering was noticeably heavier. I don't notice it now though, the car handles like a dream.

You need a few more sets of phone dials before it gets sad. Ask me how I know...