Tire Sizes

I am excitedly trying to fill the gap between ordering my kit and it arriving (hopefully in March!).
Four of the "to find here" items are the tires to be fitted to the Simmons F90 5-spoke 16 x 10 wheels.

What little info I have recommends 275/50VR16 or 295/45VR16. I am having trouble tracking down any manufacturer that makes these sizes
Any suggestions?
Thanks

[ December 22, 2002: Message edited by: dazzle ]

[ December 22, 2002: Message edited by: dazzle ]

Colin, Peter Ransom (GT40 Australia) seems to prefer the Simmons 17" wheels if you are not going for Halibrand/BRM replicas. I think that this is because there is a much greater range of wide / high speed tyres available for the 17's than the 16's. From memory, I think Peter said that 275's or 295's would fit on 10" rears, although Bill Bayard found the 275's were a tight fit. 225's on the front seem to be the go for the DRB.

I had 17" x 275 Falkens on my 89 Vette & was very happy with their grip & wear. Stephen Shedden has Falkens on 16" rims on his DRB & has been quite pleased with them as a compromise for road/track.

Kind Regards,

Peter D.

I found a set of Jongbloed 3 piece modular wheels for a good price. All 16". Couldn't find any tires to fit the rears, 12" wheel width. Ended up getting new 17" rims spun for the rears (for 335 width tires). Fronts at 245 width x 16 inch are easier to find. Because of tire availability, I would opt for 17" at least on the rears.

Good luck. I really want some wide (295 to 335) 16-inch tires to go along with Gulf flares but, after considerable research and emails to various manufacturers, have pretty much resigned myself to the fact that I'll need to go with 17-inch wheels. The widest 16-inch tire I could find is 245, although I'm told 255s are available in Japan.

Go to the Goodyear Site. They have two tires
Eagle HP Ultra Plus P255/50ZR16 is approved to be put on a 9" wheel and will have a tread width of 9.6".
If you use a 17X10 wheel you can get a P275/40ZR17 and will have a tread width of 9.7" Not really much of a difference.
Not only are tires cheaper but I think that 16's will look a lot better on a 40,I don't like the profile of 40-45 series tires. They are also hard to tell from a 15 from a little distance away.
Also the tire O.D. on both of these are between 25.5" and 26". I think this also is about right.
This tire has the same speed rateing as the Eagle F1 but the tred pattern looks a little more period correct. The F1's are a little softer and have more grip but the Eagle HP's will last longer. Your choice

I did a little research on this myself this morning.
I am planning on having two sets of wheels for my 40, one for street use and one for track. Here is what I have come up with for the "street" sizing.

My car will be a GT40NZ there fore I am going from the recommended tires from their site.
They recommend a 225-15 front and 305-15 rear which add up to be a approximately 25inch tall front and 27 inch tall rear tire.

These are also the recommended tire heights from ERA being 25.6 max height front and 27 rear.

As we all know, 15 inch tires in a decent "speed" rating are impossible to find anymore without going to a comp type tire.

I did some calculating and came up with these 16 inch sizes as possible alternatives.

225/50/16 Front= approx 24.8 inches tall

255/50/16 Rear=approx 26.03 inches tall

as you can see, these are about one inch shorter than the recommended 15 inch tires.
This should lower your ride height by about 1/2 an inch.

Now here is the GOOD NEWS!
A quick check on the tire rack website found 13 different speed rated tires (VR or better) that are available in both F&R sizes!!!!

Of these 13 possibilities, 2 are comp DOT type tires, which leaves 11 possible dot legal high speed rated tire brands available.
here are the models:

Michelin Pilot Sport YR-rated
Pilot SX MXX3 ZR-rated
Dunlop SP sport 8000 ZR-rated
Firestone firehawk ZR
Goodyear Eagle HP ultra-plus ZR
Kumho Ecsta Supra 712 WR
Sumitomo HTRZ WR
BFG comp T/A VR
Dunlop Sport 5000 WR
Michelin Pilot XGT V4 VR
Yokohoma Avid H4/V4 VR

the cometition tires available are the
Hoosier and the Yokohoma A032R

also the hoosier is available in a little wider at 275/45/16,,,,which adds up to 25.7 inches tall.

I believe that for a street car needing a good overall quality tire, the 16 inch is the best compromise.
The drawback is that they are around one inch overall shorter than recommended, but the available tires are of much better quality than a the 15 inch units.
This not only means a beeter grip while accelerating and cornering,,,but also a much better tire under braking is available in the 16 inch sizing.

(trust me, when I tell you, the single best way to improve the braking performance of a street driven car, is to use the highest quality tire available.)
(big brakes, for track use, are needed to resist fade under high heat/use,,,,,not shorten stopping distances.)

Although there are 17 inch tires available, the overall height becomes shorter still, and you lose precious sidewall height, which takes away from the "period look" of the car.

My #1 choice for an excellent street tire.
The Michelin Pilot Sports. They are probably the most expensive of the bunch, but I have them on my 500e "rocket sled", and am very impressed with their abilities.

For a "more reasonably priced" street tire, you may want to consider the Sumitomo.
The are about half the cost of the Michelins, and although I have no personal experience with them,,, I've heard good feedback from others who use them.

For a no-compromise autocross, track time tire, my choice is the Hoosier.
I will get the larger 275/45s for the rear of my car, in order to have the largest footprint possible.
Simply put, the Hoosier is the fastest DOT sticky comp tire that money can buy. They also have the shortest lifespan.

Hopefully the above info is helpful.
here is a link to the tire rack site: http://www.tirerack.com/index.jsp

I'm running Michelin Pilot Sports on my M5 (245/40/R18 and 275/35/R18) and can concur with Alain - so far (11000 miles) they seem very good. I must take a close look at how they're wearing.

In the dry they are great, when it's wet and cold they do well but are not exceptional. They are very quiet, maybe a little too quiet since they make very little noise when they slip which means I don't have my usual audible heavy-right-foot warning.

I'm not sure how the extra sidewall height a GT40 demands will affect their handling.

ciao

Ian

Dave,

Does the car look akward with different size wheels in the front and rear (16 and 17)? I'm trying to figure out how I can have Gulf flares, but avoid the look of 17" wheel, maybe your compromise is the best solution. Any pictures? Thanks, Max.

If not running "1075" or Gulf flairs, Alain's suggested rear tire, a 255/50/16 would be a good choice. However, the recommended rim width is 7 to 9 inches, much less than the 12 inches + width rims on the cars running the wider wheels and bodywork. No or not many 16 inch street tires are listed, by at least the Tire Rack, to fit wheels 12" + wide. That's why I went to 17" diameter rears.

As far as different diameters front to rear, I run a 16" diameter rear and a 15 diameter front on my VW. I was told the key was to keep the sidewall height about the same front to rear. With the different diameters, widths, and aspect ratios available, it was possible to make the sidewall heights close. The car handles great and they look excellent. The GT40 will use 16" on the front and 17" on the rears. Hoping for the same results both in looks and handling.

[ January 01, 2003: Message edited by: Dave Wharran ]