Upgrading wheel and tire to 17"

[carpenduh]

Looking for info on jumping up to a 17-inch wheel tire combo. I am looking to go with a 245 35 17 in the back and a 225 45 17 in front. I have found the wheels in the correct bolt pattern and spacing but have not seen any good or bad about the swap. The combination on wheel tire size comparison is the same or just a bit smaller overall.

Thanks

Gordon

[Nut124]

Not only the bolt pattern but also the wheel offset has to be considered.

Have you examined the rim to body, tire to body clearances with wheels turned all the way in both directions with your current wheels, tires?

Could make for a rattly ride and hard steering at low speeds. But cool, no doubt.

I used to break the rear diff every time I put in new, sticky, bigger tires.

[phaetn]

Indeed, it may be hard on the diff, plus the wormgear of the steering box. It also likely won't fit without a lot of rubbing. A 235/45-17 is nearly two inches taller diameter than a stock size. Use this tire calculator to see differences: https://tiresize.com/calculator/

Remember that the car was designed with 165/70-13s originally. Looking through some of my reference material, I think Fiat first started using 14" wheels on the Turbo Spiders with 185/60s (alloys had been optional before that, but still at 13"). They used the worm gear and roller almost throughout the line and only went to a steering rack with Pininfarinas in '85 1/2. Someone correct me if I'm wrong on that, but I have looked at a June 1984 article entitled "Pininfarina Azzurra Road Test" in Motor Trend that still references a worm and roller steering (cited in Fiat 124 Spider: Performance Portfolio. Brooklands Books, p.116).

Even the Abarth Rallys, which had reinforced components, still had worm and roller box with 13" wheels but 185/70s (ibidp. 61). Not sure if the actual competition ones were toughened up compared to the homologated series.

I have 15s with 205/50s on my '74. It's damn close at the top back corner on the fronts, but I do have lowering springs on. I could maybe stretch on 215, but wouldn't want to increase diameter much more. I can't see fiting a wheel/tire combo that is 1" taller (2" overall dia). As it is, the car with 205s hunts and darts all over the place as the tire will grab onto any surface imperfection, but that may also have to do with my camber. FWIW, I have relatively new control arms (with all new bushings), new tie rods, etc, so it's not a worn suspension or steering links. Play in my steering box seems acceptable (though I do have a spare if req'd).

My Cdn$0.02.

Here's a shot of various wheels as part of a Vermont Covered Bridges Tour in 2018 with FCA Chapter Northern New England:


Cheers,
phaetn

[phaetn]

Whoops - double post. I meant to edit but hit reply.

Do I contradict myself? / Very well then I contradict myself, / (I am large, I contain multitudes.)
- Walt Whitman

[18Fiatsandcounting]

Do I contradict myself? / Very well then I contradict myself, / (I am large, I contain multitudes.)
- Walt Whitman

No worries. "I am he as you are he as you are me" - John Lennon

[Nut124]

The OP is suggesting that the 17" tires he's considering are the same size as OEM. I did not check until Phaetn said not so.

Like he stated, those 17" are 2+ inches taller. Unlikely to fit.

[carpenduh]

I ended up going with 225 50 15, 195 55 15 wheel and tire combination. The 225 50 15 fit perfectly with no issues at all in the back. Went with 195 55 15 in the front for a staggered profile and those fit excellent as well. The slight amount of stretch by using an 8-inch wheel in front with the correct offset tucks it up underneath and gives the exact look I wanted and it handles so much better than it did before. Thanks for the advice it stopped me from buying the wrong size tire