Hello
What are the largest size wheels that can go on a 1978 X1/9 without having to modify the wheel wells?
Thank you for your help.
Stephen:
To answer your question directly, the largest size wheels that came original equipment on an X 1/9 are:
- in the 1980's on Bertones a 5 1/2" x 13 (like the Speedline "Iron Cross". The OE tire for that fitment was 185/60R13. tire OD is 21.37"
- starting in 1979 Fiat fitted the cars with 5 x 13 steel wheels with a 145SR13 with tubeless wheels for the first time. tire OD is 22.29".
- from 74 to 78 Fiat fitted the cars with 4 1/5" x 13 steel tube type wheels with 145R13 tires.
I worked for a major Italian tire manufacturer as an applications specialist for 13 years. Also, I have owned and driven five X 1/9s since 1981.
And raced one and won the NorPac Division SCCA National championship in 2005 and 2009.
So far, no one on this post has asked you what are your goals? Like, do you want a car that looks fine or one that drives good?
Since no one else has pointed this out, it is time to point out the obvious:
-What is your level of driving skill? Have you mastered controlling the car on a snowy, wet, or flooded road with the OE wheels and tires?
-If not, you should stay with OE. Here is why. If you cannot control the car with narrow, 45 year old technology tires, here is what will happen when you put modern tires and wheel with more grip: When you lose control, whatever you hit, you will hit it a lot faster and the impact will be a lot harder.
Some people who have 300 horsepower need to have more grip. You can tell if you need more grip if you upshift into second and you have to let off the gas so you do not smoke your tires. About the best way to slow down a stock X 1/9 is to put wider tires on it. Why? Low profile tires have higher rolling resistance. That means it takes more power to make them roll.
Another thing that our friends have not mentioned is "what is the effect of putting a low profile, wider tire on my X?"
It is important to consider the overall diameter (OD) of the tire you choose. If you select a tire that has a different OD, your speedometer readings will no longer be "accurate" and more importantly, at a given road speed, the amount of revs the engine is turning is changed from standard. A smaller diameter tire causes higher revs and a larger than stock tire gives less revs. If you drive your X on the highway, you may have noticed that the revs are high at highway speed compared to your modern car. That makes the car noisy and uncomfortable on highway trips. If you do not care about noise and prefer rapid acceleration, a smaller OD tire may suit you. With a stock or street modified 1300 or 1500 X, here are what I have found suits me:
Cheap choice: find a set of 79-on 5 x 13 X 1/9 wheels or the OE 5 1/2 x 13 alloy wheels. Get a set of new 175/70R13 tires. I am using Michelin Defender.
Lets say you are really cheap and never drive in the rain and want maximum grip for track days. With the 5 1/2" rims, get a set of used 185/60r13 tires from a spec racer Ford racer at your local SCCA Regional or National road race event. The fastest guys who want to win, buy new tires every weekend. After each heat cycle, they get a percent or 2 slower. Since they want to win, they get rid of the tires after 5 or so heat cycles. You can get these used for free or $20 each if you know how to shop. They are useless in the rain... This size is the spec front tire for this class of car.
The 205/60R13 are too wide for 5 1/2" wheels and will rub on the fender.
Note: These "race" tires have no grip until they have heat in them, so if you are not a track day junkie, stay away.
Some more tire ODs:
195/45R13 19.9"
195/50R13 20.7
195/50R15 22.9
185/60R13 21.37
To summarize: Wider is not always better. Some modifications will make your X more unpleasant to drive. Some aftermarket wheels because of wrong offset will cause fender rubbing even with stock OD tires. You do not have to spend $1200 to get a great wheel tire combo for your X.