Mid Year Tire Fit?

[Bill S.]

My white 66 coupe with knock offs and white wall 205 75R 15 tires are ready for replacement. I want better handling and after searching the archives it seems that 215 70R 15 is the pick. The revolutions per mile is supposed to be closest to stock and they are going to fit in the wheel wells withour rubbing.
I have just about purchased the Pirelli 400 Touring at Tirerack --- $57 each and $36 shipping for four, no tax and no disposal fee --- sounds like a good price.

Has anyone bought tires from Tirerack on the internet? These will fit without rubbing --- correct???
Thanks
Bill




Adirondack NCRS

[Mike S.]

Re: Mid Year Tire Fit?

Bill -

I purchased a set of 215-65R-15 Pirelli P6000s from Tirerack - great service and prices - for my '66 with KOs.

215-70s may fit your car without interference - or they may not. Before purchasing my tires, I looked at a lot of midyears at Carlisle and Corvette Expo with 215-70s and 215-65s. I prefer the wheelwell-filling 215-70s, but on some cars it was clear that one day a steep driveway or speedbump was going to result in unplanned body modifications. I concluded that the 215-65s provided an extra margin of safety because of the slightly smaller diameter.

These old cars don't always sit square on the frames, so you may plenty of clearance on one side but not on the other. Mine is fairly even, but turning the steering wheel all the way to the right will cause the right front tire to just begin to polish the frame ever so lightly.

Hopefully you can find a fellow enthusiast with 215-70s on KOs who will let you test fit them on your car. Good luck with your project.

Mike S
#33053

[Jack W.]

Re: Mid Year Tire Fit?

have bought plenty of tires from tirerack (for my Avalanche, my old Pathfinder, my Envoy and now my 65 C2), they have great prices and they have even called me when they noticed I was ordering a tire that was out of spec for my vehicle, just to make sure I knew what I was doing. Your biggest prob with going this route is getting someone to mount them, most majors only mount tires you buy from them, you need to visit with your local trusted "service" station, probably., for "not bought there" mounting.

p.s. 215/70R15 Firstone Indy 500 Firehawks (goldlined by Diamondback) on my 65 with the KOs, no issues at all but then again I don't have a full-lock-turn-big-bump test track, enough folks have mentioned it though that I do pay attention to the situation when it arises. It WAS tricky getting that 5th tire up in the tub, but it worked (used the Goldline length tire tray bolts, had to back the fronts out a bit even then). I have posi, don't need any mis-match tire size issues in the event of a flat.

[Stephen P.]

Re: Mid Year Tire Fit?

I've had Michelin 215-70R15's on my 65 coupe for about a year. Haven't had any contact yet with the body yet. I drive it a couple a times a week year round. The previous owner was using 205-70R15. They seemed too small for the wheel wells to me.

[Mark H.]

Re: Mid Year Tire Fit?

Duke Williams wrote two excellent articles in the Restorer (Spring and Summer 03 issues) that speak to tires - size, type, etc. The articles focus on police pursuit tires, but these are 225s and 235s. In the 215/70R-15 size, FWIW the article mentions the P4000 Super Touring, not the P400, and the Michelin Energy MXV4 as "the best performing tires available for vintage Corvettes with the possible exception of the [expenxive] vintage Michelin XWX, available exclusively from Coker Tire."

[Duke W.]

Re: Mid Year Tire Fit?

Agree with Mark 100 percent. If you are serious about performance spend the extra 25 bucks per tire and buy the 215/70ZR-15 Pirelli P4000 Super Touring, NOT the P400. Use the Tire Rack price to comparison shop locally. If you buy them directly from The Tire Rack and don't have a local installer, they can refer you to a local shop that will install them. Consider in your price analysis that shipping will cost about eight to ten bucks a tire (They can quote shipping based on your zip code and FOB point.) and you don't pay local sales tax, but the installer will charge you for mounting.

If you purchase locally the shop usually includes "free" mounting, but wherever you purchase them will charge about eight to ten bucks for spin balancing. They can spin balance dynamically by using stick on weights on both sides of the wheel on the inside.

All the anecdotal evidence I have from owners is that the above tire will fit on a mid-year with KOs without fender interference. You might get tire interference with the frame at full lock, but this is not an issue since it will only happen at very low speed.

Top off these tires with a "performance" alignment and a set of urethane bushings in the front anti-roll bar links and you will have a VERY good handling car.

Over the years I have bought many tires from The Tire Rack and never had any problems with the deals.

In any event, you're only looking at a total cost in the neighborhood of $500 for the best performance tires you can install on a vintage Corvette that will last at least 40K miles of normal driving. A set of tires on a new Z06 will run over $1200 and if you drive it like an old lady you might get 25K miles.

Good handling and safety starts with the tires. Don't scrimp!

Duke

[Paul L.]

Re: Mid Year Tire Fit?

I have used Dunlop Axiom 215-70R/15 tires on my 1967 with no nasty surprises. I will be upgrading to the Pirelli P4000 tires today (same size). While the tire width (215mm) is the same, the tread width on the two is different. The Dunlop is 6" and the Pirelli about 7 1/2". This does cause me some concern I must say. I will let you know later how things turn out.

[Mark H.]

Re: Mid Year Tire Fit?

Duke:

What specs do you recommend for a "sport" alignment on a C2 (mine is a '64, L75 engine), front and rear?

[Duke W.]

Re: Mid Year Tire Fit?

My recommended "touring" alignment settings are front camber zero, front caster +2.5 (for power steering, +1.5-2.0 for manual steering) rear camber minus one-half, and 1/16" total toe-in (1/32" per wheel) front and rear for radial tires. Make sure the rear toe-in is equally divided on both sides - 1/32" per wheel relative to vehicle centerline. (Thrust angle as close to zero as possible.) Modern four-wheel alignment equipment should show this. Also, have your alignment guy endeavor to set caster and camber as close to equal as possible on both sides.

For "sport" settings a slight increase in negative camber to minus one on
both ends should provide better handling without excessive inside wear,
especially if you do a lot of spirited cornering. I also highly recommend
changing the front anti-roll bar link bushings to hard urethane. The OE
rubber pillow block bushings that mount the anti-roll bar to the frame are
okay.

The combination of front negative camber and effectively stiffer front bar due to the hard link bushings should noticeably quicken steering response and reduce perceived understeer, but ultimate grip is determined by tires. If you have rock hard non or low speed rated 205/75R-15s, I don't think the "sport" settings would make much improvement, but would help if you have genuine performance oriented tires that I will broadly define as at least a speed rating of "H" and a wear rating no greater than about 400.

Modern equipment usually measures toe-in in decimal degrees rather than inches. Toe settings in inches can be converted into degrees with the following formula:

Toe angle = (toe-in) (2 PI)/ tire radius.

For a 215/70R-15 1/32 inch toe-in per wheel would be:

.03125 (6.2832)/13.5 = approx. 0.015 degrees.

If the alignment guy can't make this calculation, with or without the help of the alignment machine, go elsewhere!

Duke

[Duke W.]

Re: Mid Year Tire Fit?

Where did you get the tread width dimension of 7.5" for the P4000? Seems kind of high! Tread width is somewhat subjective depending on the shoulder geometry. Higher profile tires often have a somewhat rounded shoulder, which makes it somewhat difficult to define the actual tread/shoulder boundary.

Lower profile tire typically have a much better defined tread/sidewall boundary.

I just checked the Pirelli Web site and the 215/70ZR-15 P4000 Super Touring is no longer listed - just two sizes left so it appears to be out of production.

http://www.us.pirelli.com/en_US/tyre...productid=2594

They are still listed at The Tire Rack, but existing stocks may be all that's left.

Duke

[Steve Pettit]

Re: Mid Year Tire Fit?

Duke,

Probably a stupid question, but when I go to order the 215/70ZR-15 P-4000 Super Touring tires the only thing that I can find is a P4000 with a WR instead of a ZR. Is this the same thing and I just don't get it, or am I on the wrong track (so to speak)? Thanks for all your help. You guys answer questions before I even know to ask them generally.

Regards, Steve Pettit

[Duke W.]

Re: Mid Year Tire Fit?

If you look at the sidewall of an actual tire, the size is 215/70ZR-15. The Z-rating is "over 149 MPH" with no upper limit, but can be modified by the speed symbol "W" or "Y", in the service descritption that follows the size designation on the sidewall, which places an upper speed limit of 168 or 186, respectively.

I think The Tire Rack choose to place the "W" in place of the "Z" in the tire size as a short hand way of listing the speed rating, but this nomenclacture does not follow to industry standard.

You will find a similar situation on modern Corvette tires. They are "Z-rated" with a "Y" in the service description, which means they have an upper limit of 186, which is GM's claimed top speed for the new C6 coupe. (If Z06 gets the anticipated 500 HP it will be capable of 200, but may have a speed limiter due to tire limitations unless GY develops an unlimited Z-rated tire. GY does supply an unlimited Z-rated tire for the Ferrari Maranello.)

If you have The Corvette Restorer issues from last year with my two part tire article, you may want to review it for and explanation of speed ratings, service descriptions, etc. - all the information that can is helpful in evaluating and comparing tires.

Duke

[Dean Bailey]

Re: Mid Year Tire Fit?

Duke, very interesting thread regarding Mid Years. Do you have any recommendations or experience with C1 - Radial tire alignment geometry?

[Steve Pettit]

Re: Mid Year Tire Fit?

Duke,

I joined after that article came out. Thanks for getting me straightened out,

Regards, Steve

[Paul L.]

Re: Mid Year Tire Fit?

Duke,
You may recall that I took your advice last winter re the Pirellis when I was ordering the AR Torq Thrust II wheels. They were installed today and although a bit tighter than the Dunlop Axioms, they fit. I did a 20-mile run and there is no fender interference. Not NCRS but I like the look. My stock ralleys will be preserved of course!