Front tire size

[jopper]

I'm running 245/60/15 in the front and would like to run a smaller size to get the tire under the fender a little more. Is anyone running smaller sizes. I would like to know what size and if you have any pictures.

Jerry

[Excaliber]

Thats not a "big" tire your talking about, a fairly typical size. 60 series are "taller" than 50's but NOT wider. Perhaps your rims are not off set enough?

Changing rims could get expensive, you could go with a smaller tire if you want it more "tucked in". But I'm not sure even a smaller tire would look more "tucked in" than what you got.

[clayfoushee]

I think Ernie's right. It's probably a back offset issue with the wheels. The offsets are different for various types of replicas depending upon their chassis design. I'm not familiar with what it should be for E-M.

For example, I'm running exactly the same front tire size as you, and mine are tucked in perfectly.

[Clois Harlan]

Jerry,

I am running 235-60 x 15 street tires and my front rim backspacing is 4 1/2". Several of the guys around here are running 225-60 x 15 street tires on the front. My front racing slicks are Hoosiers 25.5" x 8.5 x 15.

Clois

[jopper]

Thanks for the quick reply guys. I have Team III wheels. The fronts are 7" and I think I've got 4 1/2" backspacing. It's the most backspacing they would give me without the hub being too far out of the rim. My tire is about 3/4" outside the fender. The 245's are 9.6" wide. I was thinking about going down to the 225 which is 8.8" which would bring the tire in about a half inch. Would a tire smaller than 225, maybe a 205 look much too small?

The E-M's typically have the front tire out too far.

Jerry

[HighPlainsDrifter]

Jerry,
I run the same size tire as the Grand national Buick,
it's 215 / 65 x 15

this is the perfect size for handling and less drag in a straight line.

Perry.

[Ant]

The 245/60/15 tires that are available, apart from Hoosiers are either S or T rated, that is 112, or 118 mph, not to flash, for cars that are capable of generally around 165mph.

I have gone for 235/60/15 Bridgestones H rated, and Toyo 295/50/15 with the same rating, I dont give a stuff about mixing different brands, but my local tire dealer has a Toyo 225/60/15 coming today for me to look at. The 235/60/15 is about the right size for a 7.5" rim.

Regarding tires wheels poking out of fenders or mudguards, forget going smaller in tires, as the car will look stupid if you go overboard to cure that problem, and if you get more offset to the inside of your rim that looks stupid as well. The bottom line is either shorten your suspension arms, but thats only if they are amply long enough, or do what I am doing moving pickup points and shortening my rack steering. This job is a major and requires a lot of research, making a model or using a computer program to adjust the best pivot points, and steering rack position.

My $1 worth

[RallySnake]

Jopper,

I'm with Ant on this. I do not want to worry about a blowout at over 100. Gotta have at least H rated tires.

I want neutral handling with controllable 4 wheel drifts. That means the contact patches have to be about the same size. I tried many sets of tires trying to achieve neutral steady state handling. It did not happen until I put 275/60/15s all around. Yes, the fronts stick out of the fenders a little and they look too big. But, look at the FFN spec racers. They are all running large front tires to get the balanced handling.

So, the front tires need to be very close in size to the rears for handling, say 265 or 255 section width. They need to fit 15" rims and be H rated. There's only two tires made like that. One is the Scorpion made by Pirelli. It is a VERY noisy tire. It comes on certain pickup trucks and rumbles like a steam roller. The other one is a new tire made by a Chinese company called Maxxis and it's called the MA-S1 Marauder. It's also made for light trucks and we will not know it's strengths/weaknesses until one of us buys some and finds out. I will need two tires in about 6 months. I intend to get the Maxxis tires and write a report here. Unless someone beats me to it.

See: http://www.maxxis.com/

I wouldn't worry so much about a little tire exposure. Haven't you heard, "wider is better"!

Paul

[Excaliber]

The BIG letter Goodyears (NOT DOT approved) old bias tires I'm running are amazing! EXCELLENT traction dry or wet! WAY better traction the Mickey Thompson competition tires they replaced. Very controllable when the back end breaks loose, but have NOT yet had it in a four wheel drift (coming soon)!

A little "choppy/bumpy" for the first few miles in the morning but I LOVE the "feedback" these tires give. I'm SOLD on 'em!

I have no idea what their speed rating is, all though they felt pretty smooth at 135 mph. And no idea what size they are in "metric" terms. 26.5X10X15 in rear. 26X8X15 in front (I think thats what it was). They tuck in nicely!

[Ant]

RallySnake,

I agree with you, on my car, the biggest tires I will be able to fit are the Goodyear slicks at around 26" diameter etc.
Running 275/60/15 tires on the front at 28" tall wouldn't be an option as they are massively tall and the car would have to be raised at least two inches up to about 7" ground clearance!

I dont thing you need to go so close on the front end, to your rear tires for handling, I am sure the Goodyear slick combo works well! I wouldn't mind some 245/60/15 or suchlike as the 235/60/15 are bang on but wouldnt want to be any smaller!

[Ant]

I tried a Toyo Proxes TPT 225/60/15 on my 7.5" Trigo today and "too small"
so back to the 235/60/15 Bridgestone H rating, these tires look good with the Toyos on the back, sure they aren't real sticky type tires, but now we know how much wider the Goodyear slicks are, and can basically start to set the cars suspension up!

Diameters are:
Toyo 295/50/15 26.5"
Bridgestone 235/60/15 26.2"

Going down to 215's and 225's gives approx 25.5" or less, big difference in looks.

I suppose in a nut shell I now have good speed rating and perfect diameter compared to the original car! Also in NZ I can have them in about a day!

[RallySnake]

Ant,

I've searched the Bridgestone/Firestone and Tirerack websites and they don't sell the 235/60/15 Bridgestones here. Must be an NZ only product. I wonder how much it would cost to ship a pair toi the US? These are the Potenza G009 model right?

I'm beginning to think about what Perry said. Maybe my concept of the "right" size is wrong. If a 3,000+ pound sedan can handle well on 215 mm wide tires, why not a 2,500 pound Cobra? But then, the NASCAR boys are running 10" wide slicks and they are the same size all around (except for stagger) and they're running the speeds that our cars are capable of, right? If a narrower tire worked, they'd be using them wouldn't they?

No, unless I can get your Bridgestones, I think I'll try the Maxxis.

Paul

[Ant]

RallySnake,

The tires are Bridgestone Eager 235/60R15 HR S340 RWT, NZ$213 each (USD$128.94) I would not go smaller than these, if I could get suitable 245/60/15's they would be on the car.

They are probably available ex Japan. I was looking at importing Goodyear Eagle GTII tires, which are only a few dollars more from the Goodyear/Dunlop people that bring race tires in, but as mentioned S speed rating, but they might be a better tire as far as grip etc goes, and I am not sure whether its worth taking notice of a speed rating, as I have never before in the past, I used to do approaching 160mph on skinny cross ply tires in speed events, in an old aussie Monaro.

[badrich]

Jerry: I presume you are running negative camber, but if not you might consider up to a couple of degrees negative camber. Tire mileage might suffer a tad, but the increased cornering ability will be worth it. And the top of the tires will tuck in a little bit. Good luck. Rich

[Ant]

badrich,
putting negative camber on is one way of helping a clearance problem. If your wishbones are designed, to already give 1 degree negative to 1" suspension travel, you might already have enought camber change built in. From my limited experience with suspension a bit more negative is better than positive camber - so its a fix.

Some Cobra manufacturers, builders like myself just dont put enough thought into design, or get wheels specially made for their cars, and when you want to fit original Trigo or other wheels, all sorts of problem arise.

The bottom line is start with a body/seat and four wheels, and then build the rest. Knowledgeable people write books on building race cars but people like myself (use to) pick out some excerpts and then make the usual balls ups!

[A Cobra guy]

Jerry, I'm running 245 /60 /15s on my EM. The fit nicely under the fenders. I see you have a jag rear. What is the front? Mine is the Mustang 2 geomintry (sp?) You can adjust the toe with shims. My guess is the problem is a-arms or spindles or both. None of the above will be cheap to change, so trying toe in and narrower tires makes alot of sense.

FYI I am running Yokohama Avids this year. THEY ARE GREAT. Much better than the Goodrich's I took off. If they make it, I'd bet the narrower Yokohama will corner just as well if not better than the Goodrich.

Harvey R

[RallySnake]

Harvey,

Can you tell us more about the Yoko's? In what respects are they great/good/bad?

Paul

[Excaliber]

BFG T/A's arent "all that". A number of tires do a better job, in my opinion. Yokos being one of them! I ran the AO32R Yoko auto X tire. Night and day difference after switching from T/A's.

.......whats the deal on the "Avids" I wonder?

[A Cobra guy]

The Yoko's are P245/60/R15 in the front and P295/60/R15 in the rear. They are the exact same height & width as the BFG's. I have not autocrossed with them yet but on the street I can tell them have more grip. The ride is quite and I think they are picking up / throwing fewer rocks. The tread pattern looks good and should be good on wet roads. I've had them out on damp and they were fine.
They also fixed a problem I had been living with for 20,000 miles. Durring a long, medium radius turn (On ramps and such) the front would squirm. By that I mean it felt like the power steering was cutting in and out. It was an odd pain in the but, but not a big deal. I figured it was a steering rack or front end design issue, or an outside chance it was the tires. I had pretty much ruled out tires because last fall they were worn down pretty much to the wear bars and I still had the same squirmy feel. No other change to the front end this winter. Just the new Yokohama's and the squirm is GONE.

Go to Tire Racks web site for more info. that's where I did my research. I took there prices and went to a local Yoko tire dealer who matched the price from tire rack. They balanced up well. I've had BFG's that in my opinion needed an awful lot of weights to get them balanced.
There are other threads here that talk about tires.

Harvey R.