275 vs. 285 For The Front

So, getting ready to order new shoes (Pilot Super Sports from VPA) for the project Viper and wondering if there's any downside to going with the 285's on the front?

Thanks!

This is directly from an SRT Viper engineer. Now he is talking 295 so I'm not sure its entirely the same thing and he is discussing the PS2. However the comments about rim size and camber may be applicable.

"I contend that the 275 Viper PS2 tire is stickier than the 295 PS2. That 295, being a rear Porsche tire, likely has the standard, less sticky PS2 compound and less construction (sidewall stiffness) than the Viper front. Combine the lack of construction with mounting it on a 10” wide wheel (a little narrow), and the steering response will likely be poor. It will also likely require more front negative camber or the car will push more. It is all speculation until you run a test, but I suspect the 295 front will be a step backwards. Too bad the Pirellis aren’t out, yet! I see that there are two 295/30R18 PS2 tire specs (both Porsche). It would be nice to know the differences between the two compound and construction wise. Another interesting test would be the 275/35r18 Pilot Super Sport front and the C1 ps2 Viper rear. I have been bitten more than once putting a rear tire on the front and having it not work well."

Even though the SRT Viper engineer had some good points, it really isn't the question being asked here. In this case, ROCKET62 is asking whether or not the difference between a 275 and a 285 width tire that have the same rubber compound and construction would be noticeable, or worth the extra coin. That being the case, I'd say the 285 PSS would give the front more traction over the 275 PSS, all else being equal. That's what the extra rubber buys you, and on a non-ACR Viper, it should help reduce understeer that these cars have designed in right from the factory. The discussion you quoted references possible differences between the PS2 C1 Viper Spec tire and a standard PS2, which are definitely two different tires, making a direct comparison to this case impossible.

Steve M said:

Even though the SRT Viper engineer had some good points, it really isn't the question being asked here. In this case, ROCKET62 is asking whether or not the difference between a 275 and a 285 width tire that have the same rubber compound and construction would be noticeable, or worth the extra coin. That being the case, I'd say the 285 PSS would give the front more traction over the 275 PSS, all else being equal. That's what the extra rubber buys you, and on a non-ACR Viper, it should help reduce understeer that these cars have designed in right from the factory. The discussion you quoted references possible differences between the PS2 C1 Viper Spec tire and a standard PS2, which are definitely two different tires, making a direct comparison to this case impossible.

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But he makes the point that additional camber could be necessary for a wider tire and the wheel width starts to become a problem with wider tires, maybe not the 285 though.

Is the PSS 275/35/18 not intended for Viper use or is there a C1?
So which would be better for a non ACR Gen IV, the PSS or PS2?

Sorry, in OE size?

gb66gth said:

Is the PSS 275/35/18 not intended for Viper use or is there a C1?
So which would be better for a non ACR Gen IV, the PSS or PS2?

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That's a good question. The Viper specific PS2 with the C1 compound designation has the same compound as the Pilot Sport Cups. This is why they are so sticky and typically have had rave reviews from Viperholics. Other PS2s do not generally have this same compound (although I'm told there is a Vette PS2 that does). (The C apparently stands for Chrysler, or so I've been told). No one that I've found including Luke at Tirerack can tell me what compound the PSS in Viper sizes have. If it has the same or better compound than the PS2-C1 it should be terrific but it is possible that it has a compound and tread design superior to a regular (non-C1) PS2 but not as good as the PS2-C1. This might make it better than a regular PS2 but not as good as a PS2-C1. The SRT engineer points this out. If you use a 295 PS2 for the front then it does not have the same compound as our 345 Viper OEM rear PS2. That's because the 295 was originally designed for a Porsche. Tire manufacturers design tires for specific vehicles and can and do change compounds to meet the specs the car maker gives them.

Now personally I want to try the PSS so I've just put a set on my ACR but have not taken it to the track to test yet.

A 285/30/18 is shorter then the stock size and has a less forgiving sidewall hight, I can see exactly why the 275 is the better choice.

I have a set of the new super sports they are soooo much better than the p2 I love them, Im running the 285-35 18 up front and they work great they also fit better on the rim.

mjorgensen Woodhouse said:

A 285/30/18 is shorter then the stock size and has a less forgiving sidewall hight, I can see exactly why the 275 is the better choice.

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The PSS in question here is a 285/35, so it will have a bit taller of a sidewall than the 275.

gb66gth said:

Is the PSS 275/35/18 not intended for Viper use or is there a C1?
So which would be better for a non ACR Gen IV, the PSS or PS2?

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I think the better question is how much longer the PS2 C1 will be offered since the PSS appears to be the replacement for the PS2. You may not have a choice but to use the PSS if the PS2 is indeed phased out.

Thanks for all of the replies and info. Wonder if anyone can give a comparison between the Viper Spec PS2 and the Pilot Super Sport? Could be the first time in history that a newer tire from Michelin is less expensive than the one it replaced. PS2 is about $2-300 more right now than the PSS.

I've got a full set with 285 fronts on the way from VPA, but they'll be compared to the original, nearly bald 10,000 mile PS2 C1s that came on the car, so it probably won't be a very good data point.

When you decide what your going with John just give me a call at work an ill get them installed for you again. You going with different rims of the ones that came on your new snake ?

I am running a 275/30r19 on the front of my car and the roads around here that we have make the car pull like crazy following the ruts. I would imagine it would be ever worse the wider the front tire.

LOL, the road I live off of sometimes pulls the Viper into the other lane if I don't correct it My other favorite road, International Bvld heading into Daytona is getting repaved now so maybe it won't beat you death in a Viper.

craig_g said:

I am running a 275/30r19 on the front of my car and the roads around here that we have make the car pull like crazy following the ruts. I would imagine it would be ever worse the wider the front tire.

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True that! I've got 275's on my stock wheels and 285's on my new set of wheels. Honestly, I seem to get thrown around pretty bad in both sets regardless of which I running because of ruts in the road.