GTV Tires

[brad fischer]

Bill, Just bought 205/60/15 H speed rated Sumitomo HRT A/S PO1 a directional tire that was tied for 1st in Consumer Reports tire test for UHP allseason tires. They are mounted on my new GTA 15x7 ET29mm Superleggera's.
101/105guy, Agreed different tire manufacturers have slioghtly different dia, width etc..
but most now are within .1'' of each other. In post #13 I refer to Michelin XAS as I think they were oe on GTV's at that time as well as a Pirelli and a Verdestien???

[101/105guy]

Just trying to shed some light on real tire diameters vs calculated diam.
Some try to get as close to stock as possible.....

[gigem75]

For what it's worth I've got some Summis, HTR200's 205-50-14's on my 74 Spider and they are great in the dry but get very exciting in the wet. I also had them on my GTV but put them on the spider when I got 15's and am running Potenzas, 185-60-15 currently on the GTV. Great tire, they grip lightyears ahead of the summis in the wet, great in the dry and are within 2% diameter wise so my speedo is only 2-3 mph off at 60 which is within the margin of error of any 37 yearold speedometer. Originally I thought bigger is better but learned my lesson and went with 185's and the car is much more nimble and less strain on the steering box but I NEVER turn the wheel when not moving on either car.

[60sRacer]

FWIW, here's my philosophy for street tires, at least for wet/dry performance:

I rarely drive on the street - including some wonderful ridge line two-lanes - anywhere near the limits of dry tire performance. For my daily driver, I choose tires based totally on wet performance; I want the best chances in the infrequent worst conditions. Remember that roads with infrequent rains can be extremely slick as the faint oil build-up floats to the surface from the initial coatings of rain. It takes some substantial rain on frequently used roads to clear the slick off.

Secondarily, I look for durability - I won't choose a tire that will barely give me 10,000 miles!

But for my Alfa, I rarely drive it in the rain. Also, we rarely get unexpected rain around So Cal (heck, we rarely get the EXPECTED rain - it seems to go somewhere else). So for this car, I choose the best dry performance. Also, durability is of no account, as 10,000 miles will take a few years to accumulate! I'll drive as much tread off in autocross as I will in plain miles. So I pick the best street rated "A" class semi-racing tire.

The toughest choice for me is OE skinny tires or modern high performance tires. Fortunately, when I got my 14 by 6 Pannasports, I kept the OE steel rims. So I keep a set of Pirelli's in 185/70-14 ( the OE 14 inch tire from Alfa) handy. It's less than an hour to swap them. The difference from the hot 205/60-14 autocross tires is just amazing. The car is distinctly slower, but more nimble. It's quite an enjoyable day's driving. Parking is fingertip effort, rather than a Teamster exercise.

Right now I'm struggling with finding good "A" class tires in 14 inch. I may have to get a set of Alfaholics 15 by 6 (or 7?) GTA replicas.

Robert

[spokeless]

One other consideration that I surprisingly noticed when going from a larger diameter 175(/80)-14 to a "smaller/stock diameter" 185/70-14 on the '74 Spider was an improvement in braking force.

The car had lived in the city, and I preferred the addl. ground clearance of the bigger tires. Now it's in the country, and while I do need to be careful on one particular section of road with a dip that I used to pass over cleanly, I much prefer the bite of the brakes with the smaller tires.

Barely even an opinion - just a data point.

[60sRacer]

That's such a small difference in rolling diameter (can't be much more than 0.4 inches?). More likely the difference you are feeling is due to the width of tire patch.

Robert

[spokeless]

Quote:

Originally Posted by 60sRacer That's such a small difference in rolling diameter (can't be much more than 0.4 inches?). More likely the difference you are feeling is due to the width of tire patch. Robert

[Alfie Blu]

Go to miata.net and check out their tire size calculator. It is the circumference that needs to match to not throw out the speedo calibration.

Regards,
Sid
74 GTV

[gnuts]

Quote:

Originally Posted by fangio8c I couldn't be happier with my Pirelli P4 in 185/70/14. Tirerack.com for about $60/ea. I like them much better than my previous set which was Yokohama Avid H4 in 195/65/14.

[fangio8c]

Quote:

Originally Posted by gnuts Looking for a tire that I can use on a track and the street..if that's possible ?

[brad fischer]

Your best option is 2 sets of rims one for street and 1 for track.

[60sRacer]

Quote:

Originally Posted by brad fischer Your best option is 2 sets of rims one for street and 1 for track.

[brad fischer]

Tires like 185/70/14 on 14x5.5 or 6 for the street and 205/60/14 on 14x7 or 205/50/15 on15x7 for track use. You can better choose tread pattern, compound and manufacturer when the intended use is more single purpose.

[gnuts]

Thanks for sharing your experiences. The shop will be installing 185 70 14 Pirelli's today.

[lgowin]

Let me know what you think of the Pirellis. I'm looking to get a set in the coming weeks.

Regards,
Lawrence