Thursday, October 30, 2008

Modernizing Your Spare Tire, Minimizing a Flat Tire's Hassle and Cost.

Every time we start up our cars for a drive, no one plans for a flat tire – but I am sure that it has happened to us at least once, and if it hasn’t then it’s only a question of when, it will happen. For DeLorean owners, if you have your original donut style spare, you are relying on 27 year old rubber, assuming that it can even sustain pressure. There are written accounts on forums about owners changing a flat to the spare and rolling for a few feet, before the spare disintegrates. This article is an attempt to offer an option, to prevent such an occurrence.

DeLorean, original, 27 year old wheel and tire.

The Spare Tire Issue
As with nearly all DeLorean issues, this is not new and some owners have actually taken several approaches such as eliminating, not carrying, the spare all together and ride with either Slime Sealant and a 12v compressor, AAA coverage, or just with a cell phone and credit card to call for a tow.

Current Solutions: Green Slime Sealant

Sure, Slime Sealant is a temporary solution, but it may not always work depending on the severity of the flat, rim damage, and/or how far you need to go to address the issue. (Also, if you "slimed-it" let your tire repair person know, 'cause it's going to be a messy cleanup.)

Current Solutions: Call for a non-AAA tow

Now, I don’t know about you, but I would rather change a flat with an available spare and keep moving, rather than wait in the middle of nowhere, and then pay for a tow to take the car and I home. A few times a year I do a 500 mile round trip to visit my son in college and meet up with the Central Florida DCF guys in my D, that trip is often through wide open and nearly remote areas. Should I get a flat on those trips, I’d rather address it, and move on, as I would do with my daily driver.

Current Solutions: AAA

AAA coverage is generally a good deal, but there are limitations to the amount of miles they will tow, and how many tows reimbursed per year.

Again, all the above are certainly viable solutions, but they may not work in all cases nor for everyone. So...

A Modern Replacement
So this was my goal: To modernize the DeLorean’s spare tire so that it would become a viable solution for both local and distance travel.

My search and personal preferences led me to updating the spare tire, with more modern rubber, as well as being a solution that would still fit in the wheel well (diameter and width), and since I retained the original wheel, it eliminated the guess work in which wheel would fit, and it even sort of still looks stock.

Our Donut Spare
There is no mystery about donut spare tires. Similar to our daily radial tires, they are tubeless rubber tires on metal wheels, and regulated by DOT (Department of Transportation) standards just like normal road tires. The big differences between it and your regular tires are in as follows.
Size: as they are made more compact for storage
Speed limitations: are not meant to be run at high speeds,
Mileage limitations: are not meant to be driven for any extended amount miles, just enough to get you a tire repair service station or home.
So, knowing that it should be a simple replacement.

DOT Nomenclature
First some important nomenclature on tires: DOT has specific marking regulations for tire manufacturers, to designate important information beyond size and fit suitably, notably the tires contain information on their manufacturing history. In order to update our spares, we need to be aware of these two markings, size and date of manufacture.

Size Codes
Our spares are sized for T125/70D15, which as most of you know this is the standard description for modern tires. Breaking it down:
"T" denotes a spare tire
"125" is the widest sidewall width (or 125mm)
"70" is the profile ratio of the sidewall's height, to the width (70 denotes 70% of the 125mm width, or 87.5mm)
"D" denotes a diagonal bias tire
"15" represents the wheel mounting diameter (15 inches)
Yes, this is an odd mix of metric with English units, but it is the standard.

Date Codes
This information is just as important as above because there would be no sense in replacing your old tire with something just as old. I have read that the general rule is to replace ties beyond 8 years old; however, I don’t think many people (or dealers reselling used cars) are doing that with spares, and I suspect that as long as the tread is good and that they hold air, they may have a slightly longer life. Rubber over time deteriorates as it looses its deformation properties and can harden; however for this to happen, there are also factors of environment, exposure, and usage that play into the longevity.

So, the goal is to replace your 27 year old tire with something newer. To do so, the key is to look at the stamped DOT codes to guide your replacement selection. After 2000, all tires have a two digit number to signify the date of manufacture. Easy enough, however, prior to 2000 only one digit was used, to denote the year of the decade. So a 1997 and 1987 tire would each end in an ambiguous 7. The recommendation then is to look for a 21st century tire, it will be easier to select and assure you a newer tire. The two digits before the year code, represent the week of manufacture.

For example, the picture below shows the code from my original spare, note it ends in “171”. This is a tire manufactured on the 17th week, of 1981. Visually the wheel does look in good condition, other than it could not hold pressure for over a few weeks – again, the hardening of the rubber may have accounted for that.

Where do find a newer tire?
Oddly enough I didn’t really find anyone selling spare wheels directly to consumers, and that is fine as I suspect the price would have been high, so alternative resources at your disposal are junkyards, ebay, or craigslist. Tip for looking on ebay or craigslist is to search for: T125/70D15. You will find that this is a very common size in spare tires, used on many, many vehicles so availability is actually quite good. Just make sure that you get a wheel manufactured after 2000, ask the seller for confirmation as most likely this information is rarely published.
Picture below is the spare that I found, note "0504" designator to denote a 2004 year of manufacture, and n the 5th week of the year.

Chances are also very high that you will find this tire, with it’s own unique wheel, so let’s address that next.

The Wheel
As the DeLorean's spare tire is a still commonly used size, you will find that it is mounted on a variety of wheels, and wheel patterns, depending on their host visibility. The picture below is from the spare wheel/tire that I found - from a 2001-2004 Kia Rio.

Later model Honda Civics in particular also use a 4 bolt wheel on the same tire size that our Ds use; however, it is unlikely, as in above, that that the wheel can be used due to different offsets and brake caliper configurations. Each host wheel seems unique for their specific application.

So, the recommendation is that if you find an appropriate sized good looking spare tire (some are never used), regardless of the wheel, get it and change it out with your existing DeLorean spare wheel. Any local mechanic can do that for you for a few bucks.
(I'll post a picture later of my new spare tire, on the original DeLorean wheel.)

You will find that newer spares (from 2000+) are not as readily available as 1990s spares, so keep looking around. I generally saw prices anywhere from $10-$50, but factor shipping for online transactions.

If you are curious, below is a premade search link, that displays a search for T125/70D15 spares on ebay:
Click Here for eBay Search Results.

So that’s it, once you find your tire, remounted on your existing wheel, you are ready to mount it back in the original location and drive knowing that you are ready to address a spare tire change should it be needed, and it was done for much less than the price of a tow. For you owners about to, or that have begun to, hibernate your cars for the Winter, this could be the right time for this simple project.

...or are you really ready to handle a flat, even with your new updated spare?

How would you change a flat, with your OEM jack?
Have you checked it recently?
If your on the road, and change your flat where do you put the flat as the fronts fit in spare wheel well, but the rears won't? (Tip: Best option for the rear tires is the rear luggage carrier if you have it, otherwise the passenger seat works if you don't have a passenger, otherwise tie it down temporarily to the engine mount cover.)
Seriously, if you haven’t tried it, perhaps while in your car is safe and snug in your garage or driveway, you should simulate a flat tire change on your own D.

I did that once and discovered that the my jack was flimsy, the ratchet tool for lifting the jack stripped out on use, and I didn't even have a 17mm wrench to remove my aftermarket front strut bar to access my spare! That quick exercise was an eye opener and has since been corrected by carrying the appropriate tools for the job on every drive. You should try the same, especially if you are going to modernize your spare.

>>> If you have a few minutes, be sure to check out the "Best of" postings. Thanks.<<<

No comments: