Dear Jon, just to say THANK YOU for your superb service. Packages arrived this morning safe and in perfect order. CB in the UK
• C.B. UK
Jonb, Thanks so much for helping us out! We were in a jam, with no rear-end just days before a 3 day event. In twenty years of buying Viper parts and dealing with Viper people, I can honestly say you have always been one of best best people in the business and the Viper community. Thanks for being there for all of guys that turn our own wrench. My son's and I are very grateful your business is surviving in such tough times. Now that were slowly getting back into racing, we will be turning to you for our Viper parts supply line. Sincerely, Todd
• Texas Todd

Tire Management 101

PartsRack Inc began dismantling wrecked Vipers for salvageable parts in 1998. Since that time we have noticed a common denominator in a majority of the organ-donor cars we salvage:  The tires are old, worn, hard, or mis-matched.  We see one new rear tire opposite an old rear tire; even tires from different manufacturers front-and-back.  This may seem innocuous to the uninitiated but poor tire configurations are downright dangerous.

Consider this:   If you dropped to all fours,  and tried to walk like a Cheetah (Elephant?) the total surface area of your own hands and feet would actually exceed the contact patch of your Viper’s four tires!   Your top speed would be about 1% of your Viper’s, with the same “rubber meeting the road.” If you don’t monitor and manage your Viper’s  contact patches you may be asking for serious trouble.   Tire contact also provides the direct feedback to your brain, thru your hands, feet, shoulders and butt. Called “Seat Of The Pants” (SOTP) receptors.  When your tires lose grip, you sense it thru SOTP, and your brain’s balance system, consisting  of eyes and inner ears.  It is important to have a good set of matched tires that sends the same signals to all your SOTP receptors.

Tire age is important. Every tire has a DOT serial number, stating the week/year of build. A recently televised study suggested that 6-8 year old tires may have exceeded their useful life, despite good remaining tread depth. Sunlight, oxygen, ozone, temperature, and other atmospheric factors, combined with heat-cycles of routine driving, all conspire to harden tires. The softer the tire initially, the faster it hardens. So, 3-year old race tires are much worse than 3-year old OE street tires.  Think of an old tire as a hockey puck....sliding along.

Tire construction and tread style is critical.  You would not wear a boot on one foot, and a tennis shoe on the other. And yet, owners want to maximize tire use, and often consider replacing 2 worn rear tires, while retaining hard, aged, often mis-matched front tires.  Adding fresh REAR rubber is almost always a formula to overdrive or “push” your old FRONT tires, which have hardened. Your SOTP tells your brain the rear is hooked up great, but the fronts can’t cash the checks your butt-cheeks are writing.   And if you also choose a mis-matched tread or sidewall, you may be risking disaster:  They Handle Differently.

Mixing Runflat fronts with newer PS-2 rears is also problematic, Same goes for Gen 1-2 Sport fronts, adding two PS-2 rears.   The PS2 is an asymmetrical, non-directional tire.  The Sport is Symmetrical, and a directional tire. If you mix these on the same car, the front tires corner differently from the rears!   The sidewalls flex differently, and the tread grips differently. This may be OK for your father’s Buick, but NOT for a stiffly-framed Race Car like the Viper.

Qualifier: In track events, driver alertness is 110%. Divers anticipate twitchiness and loss-of-control limits. Mis-matched tires on-track are probably less scary, because of this peak awareness.  But if you encounter a street or  highway surprise issue, (traction, debris, wildlife, idiots) you are NOT at 110% alertness. Maybe you are only at 50%.  In an emergency or surprise urgency, you are more likely to over or under-correct with mis-matched tires, and lose control.  Several anecdotes of these exact scenarios can be seen on viper message forums like www.thevipergarage.com

If you get a non-repairable tire, don’t install a single  full-tread new tire opposite a partially used, lower tread tire. You are creating a ‘stagger’ that will turn the car to the low side on both braking or hard acceleration. NASCAR teams use as little as 1/4 pound of air in a right-rear tire, as stagger to make a car turn left.  If you add 1 full-tread tire, with a used tire having thinner tread, you are taking a risk.

Like NASCAR, pay close attention to your tire pressures.   Almost every Viper Cruise I attend, someone has a near-flat tire, and they seem clueless.  That low tire, in an emergency-avoidance situation, will crash you.  Make a habit of doing a walk-around before every drive, especially after a week or two of inactivity. Even stored Vipers seep air. Carry a good tire gauge. Check your pressures when you buy 3 tanks of gas, or at least monthly.

Vipers have a larger option of tread compounds and tread styles in 18" combinations than in any other size.  You can have more control, or specialized control, with the correct tire choice. Autocross or roadrace compounds, drag radials, and several street options. Luckily, 18" wheels are available to fit Vipers from 1992-2008, with only minor changes necessary for SRT models.  Weight matters, too. 18" tires and wheels are generally the lightest available. Additional car control can be gained with lighter wheels. Easier to steer and brake, with a lighter feel thru the steering and suspension. Faster acceleration and deceleration results when rotating mass is less.

PartsRack has  access to the same tire inventories as TireRack, as well as some private deals that come our way.  Not to mention discount wheel opportunities on Forgeline, OZ-Racing,  HRE, CCW, Asanti, and more. We can almost always save you money on wheels or tires...and maybe we can even help save you or your Viper from an unsafe mistake.  

Be Safe Out There !   Your Contact Patch Matters...