Tire sizes

[J. Salmon]

OK, first of all:
1. I have less knowledge than many of your children.
2. This question should be in the appropriate section, but I've looked there.

Maybe I am confused, but many of the tire suggestions don't seem to me to be applicable on the rear, the Toyos included (225 max in a 15). As discussed elsewhere, the 15's look better but the tire choices are limited. So I am trying to see what the real options are, and I have come up with Avons and Michelin TB's, both in 295's (which is probably adequate, but bigger IS better...). The Michelins can be had in a 335, but the rim would need to be 11 or bigger, and then it seems you are welding rims like Bill has done. The 17's have more choices, but the diameter is often smaller (315 35 17 is an inch smaller D than the standard 295 50 15).

And this outer diameter is important to me. I am trying to get a handle on speed in gears with an 016. A little bigger wheel does lengthen those gears a smidge, but maybe it's not a big deal. I am just trying to be sure I am integrating the entire package (engine, transaxle, wheels, tires, brakes).

Readily available tires for road and track is important. I cringe when I think about Bill D putting a nail through one of those Avons...

[Ron Earp]

Originally Posted by salmjo1

Maybe I am confused, but many of the tire suggestions don't seem to me to be applicable on the rear, the Toyos included (225 max in a 15). As discussed elsewhere, the 15's look better but the tire choices are limited. .

Hmmmmm. I could swear that I've seen larger in Toyos, but maybe not. The Hoosiers have 275s since I have those on my Lola. I dunno, I want performance over looks and I prefer a sticky tire compared to a vintage tire.

R

[Pete K.]

For performance, wouldn't a 17" wheel be better than a 15" wheel? (Serious question, I'm not trying to start a flame war.)

[Ron Earp]

In my opinion not necessarily....

If you can get enough footprint and "stickiness" with a 15" tire, and I think you can, then the 17" tire/wheel has some negative aspects, again IMHO:

*The 17" wheel combo has a higher unsprung weight in most cases.

*The 17" wheel combo, with most of them, has the effect of numerically lowering the gear ratio in comparison to a 15" wheel tire combo. Some might want that, but I don't want that since I built a higher revving engine to cope with the numerically high gearing.

It depends on what you are doing, but if you can do it with a 15" wheel then that is what I'd use. I can run up to 15" wheels on my Jensen Healey race car. But, I use 13" wheels and cram a 225/50-13 Hoosier tire on it which is MUCH lighter than the 15" wheel and tire, has a huge foot print, and keeps my little Lotus 4 pot on boil.

And then, there is the "it doesn't look right" on 17" wheels" argument that some certainly consider valid.

Ron

[Pete K.]

Thanks Ron, great reasoning.

[Sandy]

Ron, you forgot one thing that is bad about 15" wheels, and that is usually brake fitments. You can get a good sized brake, but you can usually get much larger with the bigger rims. Cooling might also be better as well since more of the rim can be opened. The big deal for me on the 15" is that they look good on a 60's car. Ever see an old muscle car with tires that are too low profile, not such a good thing (not always, but IMHO).

In any case might not make much difference for most people. The 15" tires are limited, I spent lots of time on the tirerack looking for 15" and the fronts are not a probem, but wide rears are (street tires). 17"s have much more selection, not huge, but good enough. From Hoosiers, Kumho's, Yoko's, etc most have some tire in the 295,315,335x17 size for the rears (Racing DOT tires). For street sizes just start poking around on the Tirerack, easy to see what is available and you can check out the spec's pages they have that will give all sorts of tire dimensions and fitment information.

I think the thread started in that you were looking at the Big lettered goodyears, one thing that I'm not sure of is if these are for street use how durable they would be vs. DOT approved style tires. I was warned from where I got them is that they should not be used on the street, and I thanked him for his obligatory reading of the legal disclaimers, and he said, yes, but they really should not be on the road as they are not built for the likes of road issues encountered. I'll have to carry a can of fix-a-flat I guess

Sandy

[Ron Earp]

Originally Posted by Sandy

Ron, you forgot one thing that is bad about 15" wheels, and that is usually brake fitments. You can get a good sized brake, but you can usually get much larger with the bigger rims. Cooling might also be better as well since more of the rim can be opened. The big deal for me on the 15" is that they look good on a 60's car. Ever see an old muscle car with tires that are too low profile, not such a good thing (not always, but IMHO).

Sandy

That is true, but Fran already solved the brake issue for us - 6 pots upfront and 4 pots in the rear, Wilwoods, so that should be plenty in a < 2000 lb car. Cooling is tight, but I'm facing that on my 13" on the JH and TR8, it is solvable. One has to be neater and tidier with their cooling cans etc.

It'd all be easier with 17s though, but I have to admit I don't like the look that much and for me personally, don't see any improvement in functionality or performance.

R

[J. Salmon]

Sandy,
That is what I have noted too. Yes, you can get 15 inch tires to work, but the choices are limited, and if you were in a pinch, you could get stuck. I have thought about a set of 15's for the road, and a separate set of 17's for the track. Of course, my track time is just open track days, no racing; and I am happy on good street tires, maybe R-compounds. I don't have enough skill for slicks yet.

Just wanted to make sure I wasn't missing anything.

Oh, and if you run street tires on the track, it makes it alot harder to overheat the brakes

[Dean Lampe]

Well, here is my thought. I am considering running a cheap street tire like the BFG's and then running slicks for my second set for racing and open track stuff. What are the best track tires? I usually run the Goodyear slicks on my cobra but I don't think the fronts will fit on the RCR 40. I could spend $1000 a year on tires and that would by 2 sets of slicks. If I switch to Hoosiers or Avon's I don't think I can buy slicks that will fit for $125 each. Is that the case? If I could find an "almost slick", I could run a set in the spring then buy a second set for the end of the season. I could use the old track tires as my streets. I really only spend about 10% of the time running around the roads the rest of the time is on the track. Anyone have experience with this "perfect" tire? What ever it might be.

[CliffBeer]

Originally Posted by salmjo1

OK, first of all:
1. I have less knowledge than many of your children.
2. This question should be in the appropriate section, but I've looked there.

Maybe I am confused, but many of the tire suggestions don't seem to me to be applicable on the rear, the Toyos included (225 max in a 15). As discussed elsewhere, the 15's look better but the tire choices are limited. So I am trying to see what the real options are, and I have come up with Avons and Michelin TB's, both in 295's (which is probably adequate, but bigger IS better...). The Michelins can be had in a 335, but the rim would need to be 11 or bigger, and then it seems you are welding rims like Bill has done. The 17's have more choices, but the diameter is often smaller (315 35 17 is an inch smaller D than the standard 295 50 15).

And this outer diameter is important to me. I am trying to get a handle on speed in gears with an 016. A little bigger wheel does lengthen those gears a smidge, but maybe it's not a big deal. I am just trying to be sure I am integrating the entire package (engine, transaxle, wheels, tires, brakes).

Readily available tires for road and track is important. I cringe when I think about Bill D putting a nail through one of those Avons...

J.Salmon, re: the TBs, I've only been able to find these in the 295 dimension in a 40 series profile - this is a little low IMHO, particularly due to the gearing in the 016. 295/50 works out OK with the right 016 (5N, 3U, AAZ, AFC) but I would think the rolling diameter of the tire would be too low in a 40 series such that you're red lining in 5th at 100+ (slight exaggeration here).

Where have you found the Avons? And, in what dimensions?

Thanks.

[CliffBeer]

Originally Posted by Ron Earp

In my opinion not necessarily....

If you can get enough footprint and "stickiness" with a 15" tire, and I think you can, then the 17" tire/wheel has some negative aspects, again IMHO:

*The 17" wheel combo has a higher unsprung weight in most cases.

*The 17" wheel combo, with most of them, has the effect of numerically lowering the gear ratio in comparison to a 15" wheel tire combo. Some might want that, but I don't want that since I built a higher revving engine to cope with the numerically high gearing.

It depends on what you are doing, but if you can do it with a 15" wheel then that is what I'd use. I can run up to 15" wheels on my Jensen Healey race car. But, I use 13" wheels and cram a 225/50-13 Hoosier tire on it which is MUCH lighter than the 15" wheel and tire, has a huge foot print, and keeps my little Lotus 4 pot on boil.

And then, there is the "it doesn't look right" on 17" wheels" argument that some certainly consider valid.

Ron

Ron, agree with you that a 15 incher can be acceptable, even for track work, despite the higher side wall provided the width and suspension is tuned accordingly. The 17s ride pretty hard on the street in my experience and don't add a ton of grip in spite of the lower side wall and less deformation under lateral g's.

Obviously, the bummer with the 15 inchers is the lack of rear tire selection, particuarly with any kind of an appropriate speed rating (V or more) for a GT40....

And, I'm in the camp of the "doesn't look right with 17's"....

[Ted Reese]

Don't forget the "TD" line from Hoosier. They make a 27.5x11.0-15 that might work for a rear and 25.5x8.5-15 that might work on the front. It is in the vintage style. I ran these on my Lotus Europa (smaller size) years back. They are great drivers tires on the track. Can you find faster tires? Yes, but the TD's gave great feedback and really allows the driver to slide the car without being bitten. I drove the same tires on the street too and got decent mileage out of them. As a plus they look like vintage race rubber. Not too expensive either.

http://www.bobwoodmantires.com/hoosier/hsrhistoric.htm

[J. Salmon]

Originally Posted by CliffBeer

J.Salmon, re: the TBs, I've only been able to find these in the 295 dimension in a 40 series profile - this is a little low IMHO, particularly due to the gearing in the 016. 295/50 works out OK with the right 016 (5N, 3U, AAZ, AFC) but I would think the rolling diameter of the tire would be too low in a 40 series such that you're red lining in 5th at 100+ (slight exaggeration here).

Where have you found the Avons? And, in what dimensions?

Thanks.

I agree about the ratios on the 016 - which is why I have wanted to be sure of tire choices. I never thought the tires might affect my transaxle decision!

Here's the link to the Avons (they are a 26.7 diameter, pretty good): Tire Specs :: SascoSports

Ted,
I am REALLY liking those Hoosiers! Good price ($200), Good look (though according to the Hoosier site it is the "street" tread, which is not as correct looking as the vintage tread), big diameter (27.7), they fit a 10 inch rim, 11 inch tread width and a nice 13 inch section width, DOT labeled. Is this a tire that is pretty easy to get? Those would really seal the deal with a 15 inch wheel for me. I could use that street or track!
Thanks for the tip!!
-J.

[Pantera1889]

Here's a few pictures I took of a friend's MK V with the Hoosier TDs.

[Pantera1889]

Another one

[Pantera1889]

And another

[Pantera1889]

Another one......

[Pantera1889]

Last one for now...