Tire size - Does it have to be the same?

Hello group - my speedster has Dunlop Sport A2 - P185/65R15 tires on it right now. It was recommended by the alignment shop, that I replace one tire. Problem is - they don't make the Dunlop Sport A2's anymore, and the other 3 tires are still pretty good. Was thinking of just replacing them all. Can I go with a taller tire, to lower my RPM's on the freeway? Does that make any sense?
Simi Mike

That's a good question. In the front it might work but is there enough room for a 75 in the back? I guess you can always get a junk tire from a pile (I did that for my choice) and do a fit try, corners and such.

Taller profile (70 or 75) tyres will give you more bounce (read;softer on bumps), but slightly sloppier handling in the twisties.

Its all relative. Even a mid-1970's TR6 came stock with the equivalent of an 80 profile.

Cant compare the cheepest modern radial tyre to a pre 1970 bias-ply tyre VW came with.

Remember the rush when the first radials came out. Called them "Malcolm X radicals" !!

Mike, a 185/65 is just about right. How many miles on your tires? How old are your tires? If your tires are more than five years old I'd recommend buying new tires all round.
Ron

Relative to tire diameter: A long time ago, I put some worn out 15 inch tires on the back of my 65 Corvair, which came stock with 13 inch tires. The 15s were easily 2 inches larger in diameter. Fit fine. Wicked stance. Acceleration was weak, but OK in most traffic. Definitely lowered RPMs on freeway, BUT on some local uphills I had the gas pedal flat on the floor just trying to keep up with traffic speed. It was frustrating and a bit dangrous, as I had no evasive capability left.

Maybe it depends where you live. City traffic might be OK, but you will be flooring the gas pedal a lot more. Driving on a flat open highway would probably be OK, but any uphills may be a big problem, especialy really long uphills!

Tire diameter is all part of the combo of tires size, gear ratio and engine torque. Changing one affects all the others. IMHO saving a few RPMs on the highway may steal all the fun from the rest of your driving. Of course you could always up the power a wee bit . . .

Yes....Size always matters..

I have 145-15 in the front and 165-15 in the rear I like the Pro Street Look!

Happy Holidays!!!



kawika55

try bus selecta.com to see how the rake or lowered will look.bill

I tried P205/75/15 all around to raise my hyway ratio and they did't work out. They hit in the front fenders when making a turn and they did't fit to good in the rear. Went back to p185/65/15 and just got done installing 3.88s. What a job!

205/50/16 front, 225/50/16 rear (flared fenders, so everything fits).

Love 'em!

gn

I tried some lower profile tires when I went to my wide five wheels and they looked weird. Too much wheel well to be filled. With the lower profile you have to get a bigger wheel and slam it (ala Gordon). OK, you don't have to slam it, but it looks cooler. ;)

I wonder what the Corvair would look like and perform like today if it hadn't been killed off by Ralph Nader's book. The last year's model ( '69)was actually a pretty well-made rear engine car, for the price. My college roomate was a cop( never worried about tickets back then) and he used to cruise in his '68 Monza at 100 mph with power to spare. He couldn't take the curves as well as my old '58 356 coupe, but he smoked me when the road straightened out.

The '66 up Corvair Monza Spyder (Convertible) came with 4 carbs for 164 HP or a turbo for 180 HP. First US car with fully independent suspension - contrary to Ralph Nader the last few production years really handled well.

You giving that dope Ralph way too much credit. The same year Chevy Nova's and Camaro's with v8's of all sizes produced more power for less money. The Vair was well sorted by then but, just lost in the power wars of the 60's.

I think the vair was 164ci and 140hp with 4 carbs when all done.

Boston Bob E
www.bimelliott.com

Au-contraire, the Corvair was killed by GM, NOT by Nadir. When "Unsafe at any Speed" was published (1965), the Corvair was all ready being sold with a fully independent rear suspension. It used the same axle shafts as the 63 Corvette. At that same time, two GM top managers were vying for the GM presidency. One was the head of Chevrolet (Bunky Knudson?). His adversary used the Corvair to politically kill his opponent in the boardroom. His adversary became GM President and saw to it that GM never defended the early swing-axle design. Sales tanked, and the GM board of Directors finally killed the Corvair.

Possibly a contributing factor was the unknown cost of making an air cooled engine comply with upcoming emmisions rules. Between 1965 and 1969, there was serious consideration given to moving the Corvair into a junior Corvette position, because it's chassis was so good. It never happened.

If you like cars, "Unsafe at any Speed" is quite a good book. The Corvair is only about 20% of the total subject matter addressed.

I was working for Fisher Body Division at the GM Tech Center in Warren, Mich, just north of Detroit, from 1962 thru 1967. Chevrolet Engineering was right across the parking lot and GM Styling was on the other side of their "security wall". It was a fun time.

I'm with Boston Bob - 164ci and 140hp. The 140hp was actually quicker than the turbo 180 because the turbo spooled up so slowly.

But didn't they have a single 4-barrel version, too?

None of them wound up all that fast. I used to dust the later "Spyders" on Shrewsbury Street in Worcester with my '66 Mustang 289. The later ones also had a nasty habit of understeer, too, although "performance" suspension packages were available through Cheby dealers (if you knew the secret part numbers).

Someone used to autocross a Spyder in New England around 1970 and did VERY well with it for a few years so at least he (or she) figured out how to make it handle...

Gordon - The factory never made a four barrel Corvair, but the aftermarket did. It looked bitchin' but it never worked very good. Carb science being rather crude back then, those four long intake runners served to condense the fuel out of suspension before it could get to the intake ports. Crappy running but looking good. An after market single two barrel with long intakes was also available. Stock Corvairs had one barrels. Today you can get aftermarket triple Webers.

more trivia: I moved from upstate New York to Detroit in 1962. The drag strip times for the same Corvairs at Detroit Dragway were one full second faster than they were in New York. Home town advantage?

I changed the wheels on my 65 Corvair from 13 x 5 to 14 x 6 (plus one) and increased the tire sizes accordingly. Got a dramatic increase in cornering ability. Then I ripped the spot welds right out of the stamped steel rear suspension arm. That cooled my cornering ardor for a while.

Just to further run this off-topic, I've added a photo of my present day Corvair 6 powered buggy. 390cfm holly, oil heated carb base, works like a champ.

What was the orignal topic anyway?

Later

Bob E