MG Sports Cars

Curtis,
You mentioned in a post a while back that you had a set of 205/50R15 Falken RT-615 tires on your car but you had never tried them in the wet. I have been looking at tires and have been told they are pretty good. Have you tried them in the wet and if so what did you think. I'm also thinking about BFG and haven't made up my mind just yet.

Also, does everybody think 205's or ok or should I stick with 195 which is what I have now?

Paul

All other things being equal.... 205s will gear up the drive ratio by about 4%. Longer cruising, less acceleration. They weigh more, so more work for the suspension, also harder for the brakes to stop.
If you go for a lower aspect ratio to offset these issues, the sidewalls will be lower so the ride will be harsher.
205s stick out a bit more so will be more inclined to splash the bodywork. And the steering will be a bit less sensitive, and they're more inclined to tramline, and aquaplane.
Otoh, they have a higher ultimate dry grip.

Also depends what width wheels you have. Wider tyres on narrow wheels is not great. 195s are OK on 5.5" rims, so are 205s but 6" would be better.

Ivor (who has 215s on 7" rims on his TR6 and kinda wishes he didn't.)

Thanks Ivor, I have 15x6" VTO wheels so I should be ok with either size. I don't plan on flaring the fenders anytime soon so 115 would be too big.

Paul



Edited 2 time(s). Last edit at 08/28/2013 09:30AM by pspeaks.

As part of the "more is better" crowd I'd just like to point out that many of the ills associated with larger tires can be minimized by selection of a light weight wheel or other strategies to reduce unsprung and rotating weight. Light weight and inboard brakes for instance.

Jim

I said that? Must have been a long time ago.

As I recall, I got the Falkens a couple months before BritishV8 2008. I replaced them with Dunlop Direzza DII tires shortly before BritishV8 2013. The Falkens were fun as a track day tire. I think they were okay in the wet when new. By the time I left for BritishV8 2012 - driving in the rain for the first three hours of my trip - they didn't have much tread left. My impression is that the Dunlops are a better all-around tire, but probably not quite as sticky out of the box. Also, I think the Dunlops are a couple millimeters skinnier in the sidewall which is helpful for fender clearance... but that's just an impression. I haven't measured them.

I'm not part of the more-is-better crowd. I figure tire weight contributes quite a lot to flywheel and gyroscopic effect because there are four of them and their diameter is large. (Larger than the wheels!) Their weight is also unsprung. So, I try to compare weights for the various models I'm considering. As I recall, the Dunlops and Falkens were both relatively light for their size.

Thanks Jim, Curtis, my wheels are 13.7 lbs. each. I assume that's relatively light but I don't have anything to compare them to. I don't want to run around on rubber bands but don't want it to look like a Viper either. All the V8 MG's I've ridden in were far from stock and needed substantial tires but my 302 is stock, probably not going to be much of a performer, so I think I can go a little conservative. I must say though at the time I built the engine I was driving a 12mpg 4x4 Ford 150 and needed something with a little better mpg. For twenty five years I treated my little 4 cylinder GT as a daily driver and would like to do that again. I no longer have the guzzlers so the next time the motor comes out of the B it will be a 331 stroker with aluminum heads and a better cam; there is some advantages to not having a wife to say "NOT NO, BUT HECK NO." All I have to satisfy is you guys and I don't think you're going to try to talk me out of the "Tool Man Attitude" to horsepower.


Paul

Theres nothing wrong with a Viper. My fronts are 285x30x18 and the backs are 345x30x19..:-)

Any wheel under 15 lbs is a lightweight. Lightest I've owned? Centerline Classics (before there *was* a "classic") at 11 lbs for a 14 x 7 (I think). Now that's a light wheel and MUCH lighter than the MGB wires they replaced. Seems the Minilites are pretty decent, and Carl's wheels are very light as well at I think, about 12 lbs. Couple that with a light tire and you could easily be under 40 lbs total. But you may also drop 5 lbs from the brake caliper and rotor (each), perhaps more. And an aluminum hub is good for several more lbs. In the end you have to look at total weight. So if you cut 10 lbs off the brake package, your wheel is still lighter than the Rostyles and you pick up even 10 lbs with the tire you are still under stock weights and that is easily possible with a bigger and wider tire. If your target is the stock wires it is even easier. Bear in mind, light wheels are often less durable, even forged wheels. And forged wheels that are more durable are heavier. Finding a light, strong, but attractive wheel is a real challenge, and doing that at an affordable price is almost impossible. For one thing it's like pulling teeth to get wheel weight figures.

Of course it has to be balanced against the vehicle itself. Putting the weight into the tires increases the centrifugal effects and momentum. But often lighter brakes are also stronger and wider tires often are used because of increased horsepower and therefore traction needs, in which case you have the power at both ends to offset the increased centrifugal effects. And the trade off with the narrower tires is the need for softer, grippier compounds with an attendant decrease in tread life, and a often higher purchase price. Meanwhile, the larger tires bridge potholes better, give a little more leeway at the edge of the pavement, require lower air pressures and can result in a smoother ride. When I first went wide on my tires (265/50-14 BFG) I had a friend who insisted that an increase in tire diameter was a better idea and made for a smoother ride because it rode over potholes better. He had a good point, and though I became quite adept at keeping part of the tread over the unbroken edge of the pavement I never forgot it. The MGB does not have a lot of room for increasing the diameter, but it does have some.

Anyway those are my reasons for going big. I'm not saying that's what anyone else should do, just that it makes sense to me.

Jim

Tony, there is absolutely nothing wrong with a Viper; I have two friends with first generation Vipers which is why I used them as an example, but I do love them. I was just being facetious as in a MG with Viper size tires would look a little cartoonish but a Viper wouldn't be a Viper without them. As a hot rodder I kind of like fat tires, had 16.5x15x31 Hoosiers on the back of my bucket.


Paul



Edited 1 time(s). Last edit at 08/29/2013 10:25AM by pspeaks.

Cartoonish, some might say... including part of me, but I've built the rolling diameter into the overall gearing now, so I'm a bit stuck unless I change the back end... btw, the wheels are Shelbys, but I never weighed them.

Ivor (who owned an MGC until a head-on at 50mph)

Beautiful car Ivor! I love the color and I think the tire size looks appropriate. Actually I wasn't trying to make all that big of a statement about appearance, again I like wide tires and if I had the body skills necessary to flare the fenders and go bigger I would give it considerable consideration, however, I have neither the skill or facilities. It may be somewhat fanciful to think I'm a young man again, but as I mentioned, I want to return to using my GT as a daily driver. I've gotten to a point where wide tires with no power steering might takes a bit of that away, particularly in parking lots. Still...you have to look cool when you're sitting still too.

I bet a head-on at 50mph really made you appreciate the collapsible steering column!

Paul

Well, it is a bit heavy to park, but as I've never owned any car with power steering, even speaking as the classic ten stone weakling in his 60s, I don't find that a problem (yet).

Not sure my (68) C had a collapsible column. I know I bent the alloy steering wheel in the crash. Actually most of the collapsing was done by the car I hit, a Hillman Hunter. It folded in the middle so the roof was bent. That big engine up front acted like a battering ram, the front of the C was mangled but the screen stayed in, the doors shut OK, but when one looked under the bonnet as I was able to do some weeks later, the bell housing was smashed and so was the rear axle casing.

I think that had 165s. They'd have needed to be made of glue to make it corner lol. Alas, they weren't.

Ivor

I guess the question I was asking and didn't say it was I'm pretty sure 205's will fit ok, but will they be pinched on a 6" wheel?


Paul

Paul,

[www.rimsntires.com]

Go here and on the left side of the page under tools select size comparer. You should then be at a page where you can plug in tire and wheel combinations. I used their size comparer page to determine my desired tire and wheel combination prior to having my 8.8 narrowed. I have 205 50 15's on 6.5 inch wheels.

Steve

Quote:

I guess the question I was asking and didn't say it was I'm pretty sure 205's will fit ok, but will they be pinched on a 6" wheel?

Run the 205s, Paul. You will be fine. I ran 205/55-14 Toyo RA-1s for years on the same 14x6 wheels with no issues (track day, autocross, or street). They work fine.

For extreme handling a 6.5" or 7" wheel would be a bit better, but the 6" is still in the acceptable range for a 205. I'd still be running a 205 if they didn't quit making them in a 14" diameter.

Thanks guys, I guess all my questions have been answered. I haven't decided between 50s or 60s yet but 205 it is. All I have to do now is make myself spend the money, and let the heat here in Dallas get below 104 or air condition my garage.


Paul

I guess the question I was asking and didn't say it was I'm pretty sure 205's will fit ok, but will they be pinched on a 6" wheel?

It would ok but a 195 x 60 x 15 would be better all around. with the rating of A-A-A. then select the tread wear number. The A tire will usually have a tread wear from 250 to 350 then you need to decide if you want an all weather tire or a summer compound.

Once you make those selections then compare brands.