Tire Advice

[TMA62]

Good Morning:

I have a 1963 R-1 that I am replacing the old '70's era tires that can't hold any air. I have the original wheels that came with the car. I am thinking of using this size: P215/75R15. I saw a '63 R-2 with them and I liked how they filled up the wheel wells both front and back. My question is would this tire fit in the spare tire well in the trunk?

Have any of you uses a P215/70R15 in the front and P215/75R15 in the back to increase the rackness of your Avanti?

Thanks in advance for any info or guidance that you can give me.

[Gunslinger]

The P215/75R15 may or may not fit the spare tire well as far as circumference goes as there are some variations between tires but in all probability won't allow you to close the spare tire cover flush with the trunk floor. The tire well is made for a skinny rim and narrow 6.70-15 tire and was never adjusted for wider tires when they became the norm. What you might do is find a donut spare tire that has the proper bolt circle. I found one still wrapped in its protective plastic wrap on EBay for only $30 shipped. It takes up little space in the tire well and allows for carrying other items in there plus allows the cover to fit flush. Since it would be for emergencies only I'm ok with it.

I've never used different size tires front/rear so I can't comment on that but it would seem to me that wider tires on the front compared to the rear would look strange.

[plwindish]

The P215/70R tire does fit into the tire well of my 76, but the tire does not let the lid go flat with the floor of the trunk. I don't know if the spare well was increased in size, probably not since the round crossmember goes right under the bottom of the well.

[PackardV8]

FWIW, tire manufacturers recommend a minimum of 5.5" rim width for 215 section tires.

Yes, they'll work and live on 5" wheels, just won't handle as well or get as much tread life. Neither are likely to be concerns on most Avanti.

The diameter difference between a 70-series and a 75-series 215 tire is .8". Thus the 75-series would raise the rear .4" or less than 1/2". Might be noticeable; might not.

Finding a manufacturer which makes both in a 215 is not common. Kumho was the only one I found in a quick search. There may be others.

As mentioned, the 215 will fit in the wheel well, just too wide for the cover to lie flat. However, the resultant 70/75 diameter mismatch would limit a 70-series spare to limp-off duty on the rear axle. Any distance would damage a TwinTraction unit and many miles would damage the spider gears on an open diff. A 75-series spare would be noticeable on the front but would only be more likely to interfere with the fender lip on turn/dips.

jack vines

[StudeNorm]

I bought my '63 R2 last summer with Eagle 245/60 15's on the back and 225/60 15's on the front mounted on as yet unknown steel rims. With the car being parked for the winter I simply haven't bothered to check...The rears have no problems with clearance. The fronts have a small fender rub during sharp turns going in and out of my driveway, which has a fairly severe slope at the entrance. It came with the original spare(!), which I would not drive on much further than the distance I could roll it. Essentially around the corner and to the nearest safe parking area...The doughnut spare sounds like not a bad idea.

In the past I have used 225/70 15's mounted on 6 inch Ford or Chrysler rims on the rear on Lark type cars but have run into major fender and steering hardware clearance problems trying to fit them up front. 205/70 or 75's are a much better fit and work OK on all four corners if you want to stick with one size only.

My father had 185/78(?) 15 Michelin X radials installed by the dealer when he bought his 1964 Daytona wagon in 1963. That was Studebaker's recommended size at the time. They fit the original 4.5 inch rim but the dealership advised him to retorque the lug nuts at least twice a year.

Norm

SDC member since 1973

[Avanti83]

Remember that if you have twin-traction or another form of positraction, to size the spare to the same circumference as your rear tires or damage can result.

Bob

[garyc]

I have a set of 15"x7" w/4" backspace wheels I have just removed from my "63 Avanti. There was no cleaence problems at all with using these wheels with Michelin 215/75 R15 All Season Radials. I changed to Cargar Keystone Klassic wheels for a new look I realy like. If any one is interested in the 15"x7" wheels let me know. Gary

[mfg]

I always stick with 20575R-15's when using radials on original Studebaker Avanti wheels. Anything wider looks pinched on those narrow wheels.

[StudeNorm]

Had a chance to check the wheels on my '63. The fronts are 215/65 R15 Eagles on 6" steel rims. The rears are 245/60 R15 Eagles on 8" steel rims. The rear offset is about 4.25" measured from the outside of the lip. They look like Ford rims with the larger lug nut but I could not find any identifiying marks. As stated earlier there are NO problems with rear end clearance and minimal rub when compressing the suspension while turning hard up front. Compared to the Larks the Avanti can handle a lot of wheel and tire modifications...

Edited April 3, 2014 by StudeNorm

[PackardV8]

Yes, there's plenty of room in the rear.

The problem is always in the front and not always apparent. What happens is the wider tire/wheel seems to fit and clear the suspension, drives fine, but then it encounters the perfect storm. With the wheels turned and crossing a dip which compresses the suspension, such as turning into a driveway or parking lot, the fender lip at the top of the curve comes down and the tire tread grabs the thin fiberglass. I've seen a chunk ripped out of a fender on the first drive after a $10,000 paint job. Your results and opinions may vary.

BTW, if and when I ever paint my Avanti, I'll be molding in a 1/2" diameter fiberglass tube to reinforce the fender lip.

Edited April 3, 2014 by PackardV8