1991 K100LT Tires

[mikidymac]

A frind is giving me his late father's 1991 K100LT for an indefinate loaner. It needs new tires but the tires appear to be an outdated size. Can I run radials and if so what size? I could not find a good price on the Michelin Pilot Actives so was leaning towards the Bridgestone BT45's in stock sizes. I do not want to mess this bike up. By the way I am coming from a 2005 V-Strom 650. Thanks for any advise.

[frankenduck]

http://www.motobrick.com/index.php/topic,2927.0.html

[mikidymac]

Looks like radials would have to be a mis match brand so I guess I will stick with Bias and for the price the BT45's look like the winners. What is the stock rear size? I have seen bot 130/90-17 and 140/80-17 listed as OEM sizes and the BT-45 are available in both so which one? Same question for the front, 100/90-18 or 110/80-18?

[frankenduck]

Looks like radials would have to be a mis match brand so I guess I will stick with Bias and for the price the BT45's look like the winners. What is the stock rear size? I have seen bot 130/90-17 and 140/80-17 listed as OEM sizes and the BT-45 are available in both so which one? Same question for the front, 100/90-18 or 110/80-18?

Aside from vanity, why do you care if the front and rear tires are the same brand?  There's nothing wonrg with running different brands front and rear.  My K75 has a Bridgestone radial front and Avon radial rear and handles much better than it would on any matched brand of bias ply tire.  The notion that you can't mix brands without your bike exploding is an old wive's tale.

[Scott_]

Looks like radials would have to be a mis match brand so I guess I will stick with Bias and for the price the BT45's look like the winners. What is the stock rear size? I have seen bot 130/90-17 and 140/80-17 listed as OEM sizes and the BT-45 are available in both so which one? Same question for the front, 100/90-18 or 110/80-18?

Aside from vanity, why do you care if the front and rear tires are the same brand?  There's nothing wonrg with running different brands front and rear.  My K75 has a Bridgestone radial front and Avon radial rear and handles much better than it would on any matched brand of bias ply tire.  The notion that you can't mix brands without your bike exploding is an old wive's tale.

+1 there.
I'm running a PR2 front and Avon rear on my '95.
I've used this combo 2 years ago for 12K+ miles. Last year I tried a 150/70 size on the rear in the PR2 series but I didn't like the extra effort to put it up on the center stand. So this year I went back to the Avon 140/80 size rear.

[mikidymac]

I guess my thought on mismatching tires is of the old thought that they are designed to match and I thought there might be a problem running different brands, profiles and compounds front and rear. Just one of those things I thought you were never suposed to do. I have seen the switch on the K1100's as mentioned but I thought you have much fewer size choices on the older K100. The only rear radial I could find in the needed 140/80-17 is the Avon.

If I did decide to stay with the BT-45 bias what of the two front and rear size options do you suggest?

[frankenduck]

At least at MC Superstore they don't carry the stock size BT45 of 11/90-18 so I'd go for a 11/80/18.

What size is your rear wheel?  Y-spoked 2.75 or 3-spoke 3?

Sure you're limited to running the Avon but it's a great tire.  I had no qualms whatsoever about installing one on my K75. :2thumbup:  (And since I have a 4V center stand I could've used a K1100RS wheel if I wanted to run other tires - but I figured the bike would be faster to spin up with a lighter rear wheel/tire combo.)

[mikidymac]

The bike has the Y spoke wheels. Jake Wilson has all 4 sizes and is much cheaper than Motorcycle Superstore so I just need to know the size. To me it seems that the wider and lower profile would be better but what do I know. I think I will just stick with the bias BT-45 due to cost and it is an LT.

[Scott_]

The bike has the Y spoke wheels. Jake Wilson has all 4 sizes and is much cheaper than Motorcycle Superstore so I just need to know the size. To me it seems that the wider and lower profile would be better but what do I know. I think I will just stick with the bias BT-45 due to cost and it is an LT.

You might email or contact them and find out how OLD those tires might be. You really don't want anything that's much over 4-5 years old at the most.
Some of your larger tire distributors don't have that issue of "old stock" as they have stock move through quite quickly so it's fresh. I'm not saying the Mr. Wilson has that problem, but you never know.

[mikidymac]

Do you know something I don't? Jake Wilson is the street side of Rocky Mountain ATV/MC and is one of the largest retailers in the country so I am sure they have a large turnover on their stock. Besides the rear are out of stock untill the beginning of the month so I am sure they will be fresh. I have nothing but good things t say about Rocky Mountain.

[frankenduck]

Quite a lot of those vendors ship from the same DCs (distribution centers) that have a high rate of inventory turnover so unless you're ordering something REALLY odd your chances of getting something unusably old are probably somewhere between zero and none.  I wouldn't worry about it.

[mikidymac]

Thanks Frankenduck. Just spoke with my friend and he was the service manager at a BMW dealership and said his opinion was to use the hardest touring tires I can find in the stock size on that bike. He said for what that bike is and what i am going to do with it that would be the best life. He is of the opinion that I and most riders will not ride even the hard tires to their potential. I am going to go with the sport touring BT-45's for a little better cornering in the stock size. His father was an Iron butt on this bike and it just got a $4,000 service before he passed away replacing all fluids, seals and complete engine inspection by a factory mechanic. His father passed away with 490,000 logged BMW miles, just short of his 500,000 when he passed. This bkie has 100,000 miles and all the others were on R1100's, r1150's and r1200's but he always liked this K100LT. That does not even account for his Harley miles and he only started keeping track in the late 1990's. I feel honored to be given it. Should be good to go, I feel like a kid waiting for Christmas morning.