Moto Guzzi V700, Ambassador, V7 Special, Eldorado, 850 California, 850 GT - Tires

Inner tube use in tubeless tires

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Can an inner tube be fitted to a tubeless tire?

Yes. I'm not currently aware of any tubeless tire that will damage inner tubes.

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Tire changing

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Sooner or later, you will need to change your tires. Either they will have worn out, rotted out, or been mutilated by some road hazard. When that time comes - and it may come at the side of a road a long way from help - you will need to know how to change your tires. I suppose you could wait for help or push the bike to the nearest dealer, but if you are armed with the knowledge you need and the appropriate tools, you can be back on the road and having fun a lot sooner.

Fixing a flat on a tubeless tire can be as easy as simply inserting a plug and re-inflating the wheel. But, since Moto Guzzi loop frames are blessed with tube tires, a flat always requires removing the wheel from the bike and then removing the tire from the rim.

I've watched car tires being changed at the local tire shop ever since I was a kid. But before I tackled the job myself with my new tires, I sought information. I found that information at a site that Adam Glass put together. Rather than repeat any of the information here, just jump over to his site for a good read.

Tire changing videos

Tire changing video, part 1

Tire changing video, part 2

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Tire choices

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Good rubber is a necessity. I once read that the combined contact patch for the both the front and rear tires is the size of the palm of your hand (David L. Hough - Proficient Motorcycling). That being said, just about any tire you purchase today will be better than the tires available 30 years ago.

I think it is a usually a very good idea to purchase tires as close to the manufactures original specifications as possible. Modifying tire sizes can have a dramatic effect on the handling of the motorcycle. That's not to say you can't make modifications, just that the consequences may or may not be desirable. Here are the Moto Guzzi specifications for all V7, Ambassador, and Eldorado models:

• Rim width (inside dimension): 2.15 inches
• Rim width (outside dimension): 3 inches
• Rim diameter: 18 inches
• Tire size: 4 inch x 18 inches

Here would be my choices. In making these selections, I chose touring or cruising tires because that's what I do with my Ambassador and I like to get as many miles out of my tires as is safely permissible. If you choose sport rated tires, you can expect greatly decreased tire life (but all that gooey traction will let you ride the bike up a wall).

When viewing these selections, keep in mind that I tried to find the tires I think would be best for the style of riding I do with my Ambassador. I chose to include some brands below for which the tires they currently offer don't really meet my needs. I included these selections so that individuals who choose to be loyal to a particular brand would see it listed here. In the end, the tires you choose to put on your motorcycle are your own business.

• Avon:

  First choice

  • Front: Roadrider [100/90-18]
  • Rear: Roadrider [110/90-18]

  Second choice (Avon no longer makes these tires)

  • Front: AM20 SuperVenom [100/90-18] (No longer available)
  • Rear: AM21 Roadrunner [110/90-18] (No longer available)
  • Note: This was my first set of tires on my Ambassador, only in the wider 120 width on both the front and rear. I was pleased with the traction, but I personally felt the handling suffered due solely to the width. I switched to the Dunlops because I wanted to get a longer wearing tire. The rear tire lasted about 8,000 miles. Not bad, but I'm seeing if I can get one to last longer.
• Bridgestone:
  • Front: S11 Spitfire Touring [100/90-18]
  • Rear: S11 Spitfire Touring [110/90-18]
  • Note: I am currently running these tires.
• Cheng Shin:
  • Front: Marquis Sport/Touring [100/90-18]
  • Rear: Marquis Sport/Touring [110/90-18]
  • Note: For a short time I used these on the yellow Eldorado Project Bike (until I sold the bike), they worked fine but I don't recall any specifics.
• Continental:
  • Front: Conti Go [100/90-18]
  • Rear: Conti Go [110/90-18]
• Dunlop:

  First choice (Dunlop no longer makes these tires)

  • Front: 491 Elite II [100/90-18]; 6/32" tread depth when new
  • Rear: 491 Elite II [110/90-18]; 9/32" tread depth when new
  • Note: I got 16,522 miles out of the first rear tire and 14,398 miles out of the second rear tire. I got 21,672 out of the front tire.

  Second choice (This front tire has a tendency to track pavement grooves)

  • Front: D404 [100/90-18]
  • Rear: D404 [110/90-18]
  • Note: I've never used these on the rear. I got 9,248 out of the front tire.
• Duro:
  • Front: HF261A Excursion [100/90-18]
  • Rear: HF261A Excursion [110/90-18]
• Kenda:
  • Front: K657 Sport Challenger [100/90-18]
  • Rear: K657 Sport Challenger [110/90-18]
• Metzeler:
  • Front: Lasertec [100/90-18]
  • Rear: Lasertec [110/90-18]
• Michelin:
  • Front: Pilot Activ [100/90-18]
  • Rear: Pilot Activ [4.00 x x18]
• Pirelli:
  • Front: MT66 [100/90-18]
  • Rear: MT66 [120/90-18]

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Tire size information - Alphabetic / British system

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The common format for these numbers is ABCCD-EE (e.g., MT90H-18). Explanation:

• A: This character is always an "M" and is an abbreviation for "Motorcycle".
• B: This character refers to the width of the tire as a code (see tire width conversions table below). Using the alpha codes, either an "M", "N", "P", "R", or "S" would work on the 2.15" wide loop frame rims.
• CC: This number refers to the height (aka: profile or aspect ratio) of the tire as a percentage of the width of the tire.
• D: This letter refers to the speed rating (see speed ratings table below).
• EE: This number refers to the diameter of the rim in inches.

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Tire size information - Inch / American system

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The common format for these numbers is A.AA/BBC-DD (e.g., 4.00/90H-18). Explanation:

• A.AA: This number refers to the width of the tire in inches (see tire width conversions table below).
• BB: This number refers to the height (aka: profile or aspect ratio) of the tire as a percentage of the width of the tire.
• C: This letter refers to the speed rating (see speed ratings table below).
• DD: This number refers to the diameter of the rim in inches.

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Tire size information - Metric system

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The common format for these numbers is AAA/BBC-DD (e.g., 110/90H-18). Explanation:

• AAA: This number refers to the width of the tire in millimeters (see tire width conversions table below). A quick conversion from inches to millimeters (4" x 25.4 = 101.6 mm) gives us a value of 101.6 mm. Using metric sizes, either a 100 mm, 110 mm, or 120 mm wide tire would work on the 2.15" wide loop frame rims.
• BB: This number refers to the height (aka: profile or aspect ratio) of the tire as a percentage of the width of the tire.
• C: This letter refers to the speed rating (see speed ratings table below).
• DD: This number refers to the diameter of the rim in inches.

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Tire size to use in a loopframe

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Width: Most modern tires are now specified in metric widths. However, the Guzzi documentation specifies 4 inches as the appropriate tire width. A little math will tell you that 4 inches is equal to 101.6 mm. So, a 100 tire is the closest you can get to the factory specification. It is possible to fit a 110 or a 120 on a loop and still clear the fenders.

Height: Most modern tires specify the height as a percentage of the width. As near as I can tell, back in the day when Guzzi specified a 4 inch wide tire, the tire was also 4 inches high. That is, the height was 100% of the width. Finding a tire that is the same in both height and width is not easy with many modern tires. Instead, most tires applicable to loop frames will have a height that is 90% of the width.

My first set of tires were 120/90-18 front and rear. I thought they were fine until I put on my second set of tires, 110/90-18 in the rear and a 100/90-18 up front. Wow, what a difference! My skill level in the twisties went way up immediately. The bike turns much more quickly and I love it. No more 120/90-18s for me.

That being said, some very well respected owners like to run the wider 120s.

• One reason to run the wider tires is that it fills the fenders more and looks better. If you are really interested in running a 130 or 140 wide tire in the rear, contact Mark Etheridge of Moto Guzzi Classics as he can provide you with the modified components to make the switch easy.
• Another reason is to gain a little extra cornering clearance. A 100/90-18 would give a height of 90 mm. A 110/90-18 would give a height of 99 mm. A 120/90-18 would give a height of 108 mm. So, to compare these figures, subtract the height difference between the tire sizes. Using a 100/90-18 as a reference point, a 110/90-18 would be 9 mm taller and a 120/90-18 would be 18 mm taller. These calculations are simplistic and don't take into consideration all factors...but the main point is that the height differences are real.

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Tire speed ratings

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Code	Speed rating (in miles per hour)
Unrated	95
S	112
T	118
H	130
V	149
Z	above 149

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Tires - tubeless conversion

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DISCLAIMER: DO NOT ATTEMPT THIS MODIFICATION. DESCRIPTION IS PROVIDED HERE FOR ENTERTAINMENT PURPOSES ONLY.

My conversion

Inspired by Greg Field's write-up in the MGNOC newsletter about his tubeless conversion on his Eldorado, I decided to make the same modification to my Ambassador. Here is what I did:

1. Used a hand file to dress any gouges in the rim...particularly where the tire bead will seal.
2. Cleaned the rim with a heavy duty wire wheel on my high horse power bench grinder. This did the lion's share of the work.
3. Cleaned the rim with a light duty wire wheel on my low horse power bench grinder. This got in a little better around each spoke.
4. Used a cup-style wire wheel on my dremel tool to clean around each spoke nipple. This finished up the clean up.
5. Scrubbed down the entire rim with rubbing alcohol.
6. Let the rim dry.
7. Applied standard, normal, everyday silicone to each nipple hole...a light first coating. (I used General Electric Silicone II Aluminum & Metal 100% Silicone Sealant; stock number GE5050; P-1285)
8. Let dry for 24 hours.
9. Applied standard, normal, everyday silicone to each nipple hole...a second finish coating.
10. Let dry for 24 hours.
11. Vigorously scrubbed clean a rim strip with soap and water. Then I wiped it down with rubbing alcohol and let it dry.
12. Applied standard, normal, everyday silicone to the entire "well" area where the spokes are located. Then I fit the cleaned rim strip to this area and made sure it was fully siliconed in place.
13. Let dry for 24 hours.
14. Fit another rim strip on top. The purpose of this second rim strip is to protect the sealed silicone area from accidental contact with the tire or tire irons. Since it is on there without any silicone, it is able to move and slide around a bit. I think it is a very good thing.
15. Fit a valve stem from Drag Specialities, part number VS-1218R. The nice thing about this valve stem is that it does not require enlargement of the hole in the rim.
16. Fit tire and inflate.
17. Ride.

Greg Field's conversion

Thanks to Greg Field for posting this information on the Wildgoose Chase forum. In Greg's own words:

For those who want to try it, here's an easier way to make your Borranis tubeless

The key is surface prep. Wire wheel the drop center to get all scmutz and corrossion off of the metal. Then take a conical dremel wire wheel and thoroughly clean each spoke dimple. Blow out all dirt with compressed air. Then clean the drop center and dimples with solvent. Blow thoroughly around the niples with compressed air.The key is surface prep. Wire wheel the drop center to get all scmutz and corrossion off of the metal. Then take a conical dremel wire wheel and thoroughly clean each spoke dimple. Blow out all dirt with compressed air. Then clean the drop center and dimples with solvent. Blow thoroughly around the niples with compressed air.

First sealing step is to smoosh a little RTV thoroughly into each dimple. Let this cure overnight, and then repeat. This is the ehart of the seal, so do it like your life depends on it.First sealing step is to smoosh a little RTV thoroughly into each dimple. Let this cure overnight, and then repeat. This is the ehart of the seal, so do it like your life depends on it.

Then fit a 16-inch scooter tube, and note how much rubber you need to leave in the center to fill to the edges of the drop shoulder. Cut the tube to this width, leaving in the valve stem. Mask off all but the drop center, and then thoroughly clean both sides of the tube with soapy water and then solvent. Get off all the wax and powder, so the RTV will stick well. Then scuff the rubber with sandpaper. When the tube is ready and dry, smear on a light layer of RTV all the way around the drop center. Squeeze out a bunch of extra RTV around the valve stem because this area will be held proud of the drop center by the valve-stem reinforcements in the tube. You want to fill in entirely that area with RTV. Then fit the tube, and use you finger to work out all the bubbles. When this is done the tube will look like a shrink fit into the dropcenter and will conform even down inside the spoke dimples.Then fit a 16-inch scooter tube, and note how much rubber you need to leave in the center to fill to the edges of the drop shoulder. Cut the tube to this width, leaving in the valve stem. Mask off all but the drop center, and then thoroughly clean both sides of the tube with soapy water and then solvent. Get off all the wax and powder, so the RTV will stick well. Then scuff the rubber with sandpaper. When the tube is ready and dry, smear on a light layer of RTV all the way around the drop center. Squeeze out a bunch of extra RTV around the valve stem because this area will be held proud of the drop center by the valve-stem reinforcements in the tube. You want to fill in entirely that area with RTV. Then fit the tube, and use you finger to work out all the bubbles. When this is done the tube will look like a shrink fit into the dropcenter and will conform even down inside the spoke dimples.

Then, fair in RTV around the edges of the tube, and let it cure.Then, fair in RTV around the edges of the tube, and let it cure.

Remove the masking and fit a tire. Test for leakage. If no leaks, then you're done. It usually takes less than one 3-ounce tube of silicone. If you are using more, it's likely too much.Remove the masking and fit a tire. Test for leakage. If no leaks, then you're done. It usually takes less than one 3-ounce tube of silicone. If you are using more, it's likely too much.

Pay to have it done

Alternatively, have Wheel Works do it for you. Here is an article describing what they do.

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Tire width conversions

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Permissible Rim Widths (in.)	Metric Width (mm.)	Standard Width (in.)	Standard Low Profile (in.)	Alpha Numeric Codes
Examples	###/90-18	#.##/90-18	#.##/90-18	M#90-18
1.60 1.85	70	2.75	-	G
1.60 1.85	80	3.00	3.60	H
1.60 1.85	80	3.00	3.60	H
1.85 2.15	90	3.25	3.60	J
1.85 2.15	90	3.50	4.10	L
2.15 2.50	100	3.75	4.10	M
2.15 2.50 2.75	110	4.00	4.60	N
2.15 2.50 2.75	110	4.25	4.25/85	P
2.15 2.50 2.75	120	4.50	4.25/85	R
2.15 2.50 2.75	120	4.75	5.10	S
2.50 2.75 3.00	130	5.00	5.10	T
2.75 3.00 3.50	140	5.50	-	U
3.00 3.50	150	6.00	-	W
3.00 3.50 4.00	160	-	-	-

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