Wheels and Tires


Wheels and Tires
Problem No. 4

CLICK HERE for the first 3 problems

CLICK HERE for some images of wheels


The main concern is the rear wheel. The rear wheel is 18" x 5.5"; thus there are no super sticky modern tires in the original tire size. If you want the latest in tire technology there is no option but to change the rear wheel. Honda claim the 18" rubber was to reduce tire wear during endurance racing as a result of the relatively larger circumference. The circumference is about 4% greater than a 17" tire.

The much less problematic wheel is the front. Honda got the diameter right, but then selected a 3" wide rim. The 3" wide front was selected to allow the front wheel to be removed easier for quicker pit stops. That's all history now, we just need to know is the 3" wide wheel is a poor choice for most modern rubber. A 3-1/2" wide rim looks a lot better than a spindly 3".

You do have a few choices for both the rear and the front. All choices have some monetary implications.


Just as reference this what comes on an RC30 when new. All stock wheels are plain gloss white, not the pearl white as used on the bodywork. The Honda RC30 paint codes are here. Tires are a radial rear and a bias ply front. Open this PDF to learn how to decode a tire's DOT manufacturing date. The pictures below show the original Bridgestone rubber, some RC30's came with Dunlop tires.

 

 


STOCK REAR

Wheel:

Tubeless type
  • 42650-MR7-305ZA (all countries use the same wheel), 18" x 5.5" single sided.

Tire:

The rear tire is a radial ply.

  • 42710-MR7-003 (Japan Only) Bridgestone Cyrox 170/60R18 73H CY08A
  • 42710-MR7-004 (Japan Only) Bridgestone Cyrox 170/60R18 73H CY08A
  • 42710-MR7-611 (Various) Bridgestone Cyrox 170/60VR18-V270 CY08A
  • 42710-MR7-612 (Various & Australia 89 and USA ) Dunlop 170/60VR18-V270 K855


STOCK FRONT

Wheel:

Tubeless type

  • 44650-MR7-305ZA (All except Switzerland), 17x3.0
  • 44650-MR7-306ZA (Switzerland ONLY) 17x3.5

Tire

The front tire is a bias ply in all cases.

  • 44710-MR7-003 (Japan Only) Bridgestone 120/70-17 58H G553
  • 44710-MR7-004 (Japan Only)
  • 44710-MR7-611 (Various Countries) Bridgestone 120/70V17-V270 G553 or
  • 44710-MR7-612 (Various Countries & USA) Dunlop 120/70V17-V270 K755F
  • 44710-MR7-691 (Switzerland Only) Bridgestone 120/70V17-V270

POSSIBLE SOLUTIONS - REAR WHEEL and TIRE

Rear - Solution 1

Use an RC45/RVF750 17” x 6” wheel. This sounds easy. Especially when lots of people have put 6” wide wheels on the RC30 and HRC sold them. As a general rule it doesn’t work without other modifications. Consider these topics prior to making a decision.

  1. Even the stock 5.5” wide wheel with the narrowish section Bridgestone tire is close to the swingarm and rear fender. The tire comes very close to the chain on an RC30. Inner fenders are not available from Honda anymore, keep that in mind with any tire and wheel choice. I had a 1990's era Sportmax tire in 170/60-18 that did rub the chain. Granted it was a weird/wide section for a 170.
  2. Some guys use spacers with the RC45 wheel to move the wheel to the right to gain the necessary swingarm and chain clearance. I'm too retentive for this, if the wheel was supposed to be 6mm to the right then Honda would have made it that way. They did not, and something just seems fishy to me. If your rear tire is now a 180 width on your 6" wide rim, it will shred the inner fender on the right side (or still both sides). The right tire edge will have effectively moved approximately 13mm to the right. Many people will do a poor job of the installation too. Longer pins should be installed in the axle to accommodate the spacer that would slip over them. There will never be any engineering awards for this even if it does "work". 
  3. You could grind/cut or otherwise remove the interfering part of the left side of the tire (and maybe the right if it hits the inner fender). The less said about this the better. Something has to be sacred here. Let us make it the actual construction of the tire.
  4. A ride height adjuster or adjustable length damper is needed to regain the lost static ride height (about ½”+ in height). HRC made these but they are made by others such as Max ton and Moriwaki. This applies to any 17" wheel or an 18" wheel with a 160 tire (see Solution No. 5).
The 1991 HRC kit manual shows a 17 x 6 wheel  but they don't show a spacer. Don't forget that race bikes do not use a rear fender so it won't get destroyed like it does on your street bike. If someone tells you this works, and by that I mean clears teh rear fender and everything else, get them to PROVE IT.

Rear - Solution 2

Buy an HRC magnesium kit wheel in 17 x 5.5. Yes, they made them, but they are extremely rare and usually very costly. I lean away from these wheels for anything but show use. Invariably they are used, which nearly guarantees it’s off a race bike. Race bikes have a tough life and crash a lot so hidden damage is always a concern. These wheels were also cast of magnesium alloy which might sound cool, but in reality just means they are lighter, weaker, have no street approval, and corrode very easily. Old magnesium wheels have a tendency reveal cracks when properly NDE'd. "Crack checking" methods can vary from dye-pen and ultrasonic testing to someone with big floppy red shoes listening to the wheel resonance after hitting it. I have faith in NDE, but if you are not trained in the techniques, tools, limitations, and results interpretation it can be difficult to evaluate, even for many qualified, or supposedly qualified, people or organizations. The guys who run these wheels on the street will tell you they've never had a problem. Use them at your peril, track or street. Maybe the guys who had problems don't beak off as much. Lots of people may say I'm paranoid, but there is an old saying... there is fine line between being brave and stupid.

Rear - Solution 3

Buy a cast or forged aluminum aftermarket rear wheel in 17 x 5.5. This is a good option if you can find a nice one, preferably new with some type of road approval like the Japan's JWL. An aluminum alloy wheel is more durable than magnesium alloy. Cast wheels are sometimes possible to repair but I'm with Honda on this one, get a new one if it's damaged. Cracked, bent or repaired wheels make nice garden hose reels. The problem with fixing wheels is that you may not know if it's already been nicely repaired. Might be OK if you know the history, if you do not the additional metal working, if over the same area, can be more than additive with the original damage.

There have been both cast and forged aluminum wheels made in a variety of designs from hollow 3 spoke old school, to trim looking modern forged designs. If you buy it used, or with an unknown history, have it checked by the manufacturer if they offer such a service. I'd recommend a call to the company before you send anything off. Even a new wheel should get a good visual inspection and running on a stand.  You will need special tools to test an RC30 rear wheel for trueness or to balance it. As with all 17" wheel options a ride height adjuster is required.

For the same reasons as previously mentioned I advise, as a general rule, to stay away from old aftermarket magnesium alloy wheels. I realize this might just be me. Be my guest and do as you please, just don't ask me to be part of it thank you.

These are some of the companies that used to make wheels of various materials and by various methods if you are looking for something.
  1. Dymag
  2. PVM
  3. Maxton
  4. Carrozzeria
  5. Duomo
  6. Marvic
  7. Marchesini
  8. Brembo
  9. Tecnomagnesio
  10. Delkevic
You can view an image of most of these manufacturer's wheels here.

Rear - Solution 4

Buy a new carbon composite or carbon/alloy composite wheels. Carbon fiber is poor with impact loads. That is a fact, but you will normally only read or hear statements about high tensile strengths, monumental stiffness, light weight, and other truths that don't mitigate the low toughness concern enough to satisfy me. Though the carbon fiber wheel manufacturers design around the poor material properties there are fundamental differences between a wheel made from a (relatively) ductile material like cast or forged aluminum and those made from a brittle (in the true engineering sense) matrix of plastic and carbon fiber. The manufacturers push performance gains such as lower polar moments, less unsprung weight and the like. Yes, they often have street approvals but that, to me, is little consolation. You have to be prepared to deal with wheels that are not as robust as something made of 100% metal. beside being outright tacky these wheels are expensive and finicky, not what I normally look for in a purchase.


Some gurus at an on-line forum have refuted my technical opinion on plastic wheels. What else is new? Go here to be enthralled with innuendo and horribly misapplied analogies. These types of wheels are banned in every type of motorsport racing I can think of. They are forebaden primarily because of the nasty failure mode. The reasons for my personal lack of acceptance are similar to those of the sanctioning race bodies around the planet.

OK now, lets look at it from a less technical angle. Even if these wheels possessed some real value and were truly race and roadworthy it does not stop them from being cheesy. I have done some intensive research, just as the gurus did, and developed this simple formula to explain partially what I am talking about. The equivalency is plain to see even to the most technically challenged.



Rear - Solution 5

May 11, 2012......Unfortunately I had to update this section because Dunlop has ceased to manufacture the 170/60-ZR18 (actually W rated). The Roadsmart has been replaced by the Roadsmart II that only has a 160/60-18 rear tire now. This really sucks. Hopefully they reconsider or someone else starts making a tire suitable for the RC30 in a modern construction. The bold red strikeout text below is no longer applicable.

Dec 17, 2012...... Well, looks like things have changed again. The new Dunlop Roadsmart is available in the correct 170/60-18 size, however it appears that only certain markets (Australasia etc) will be able to buy it.

Don’t do much of anything. Just go buy a 170/60R18 tire for the stock rim. This is, surprisingly, one of the best alternatives if you don’t want to lay out the funds. Dunlop introduced a dual compound sport touring tire called the Roadsmart in the exact right size, that being 170/60VR18. This tire, in spite of it being a "sport touring" tire would be better than anything available for this bike back in the 1990’s. I personally think Dunlop are out to lunch sometimes, but with this tire they seem to have hit the nail dead on. It is worth mentioning there is one other radial tire I know of. It is a Shinko Podium 006. Say what you want about them but most of the Shinko tires get good reviews from the people who try them. I haven’t tried them so I won’t say anything other than they make a correct size 170/60VR18 radial tire Shinko also make the matching 120/70ZR17 front tire so there is no front to rear mismatch I have had problems with in the past. Shinkos run about 60% of the cost of the Dunlops. To the best of my knowledge these two setups are all that is made in the exact right sizes as sets. There may be some bias tires out there also but I like radials.

I should mention that lots of people would say the Harley Davidson V-Rod tire (also a Dunlop) is available and will spoon onto the rim. Unfortunately it is a 180 section tire and, as mentioned before, will be an interference concern. Try it if you want. It's not really the best tire with no matching front either.

One variation of this option is to install a 160/60R18 tire. This size being narrower than the proper 170 section, is narrow for a 5.5 inch wide rim. Most 160 width manufacturers recommend a rim around 4.25" to 5" wide. 5.5" might be OK, but ALWAYS check with the manufacturer of the rubber first. A good tire shop could also probably advise. If you went this route you will find there are some fairly good tires available but still mostly modern sport touring tires. A suggestion when going this route would be to mate it with a 110 section front tire to try to balance the installed profiles front to rear, especially if you are using the stock 3.0" wide front wheel. With these relatively narrow tires you will end up with a flatter cross-section.

A ride height adjuster is needed if using a 160/60-18, same as with a17" rim. A ride height adjuster is a good idea even with the stock 18" rear and tire. RC30's sit low in the back and under power over bumps the tank slappers show up. Jacking up the preload is not the answer to the lowish rear.

Some of the better rubber available in 160/60ZR18 just to ponder the possibilities. If one of these was manufactured extra wide you'd effectively have the correct size and might be able to skip the height adjuster. Not all tire companies publish installed widths. You would have to extrapolate to a 5.5 inch wide rim anyway. Nobody gives an installed width for a 5.5 inch wide rim, 4.5" seems to be the norm.

  • Continental Conti Force (Sport touring - 161 wide on 4.25" rim - 649 diameter)
  • Continental Conti Road Attack (Sport touring - 161 wide on 4.25" rim - 649 diameter)
  • Avon AV56 Storm (Sport Touring - 167mm wide on 4.5" rim - 648mm diameter)
  • Avon Storm 2 Ultra (Sport Touring - 168mm wide on 4.5" rim - 647mm diameter)
  • Bridgestone BT023 (Sport Touring - 160 wide on 4.5" rim - 648 diameter)
  • Bridgestone BT016 (High Performance - 160 wide on 4.5" rim - 648 diameter)
  • Dunlop Sportmax (High performance - Looks like this one might be discontinued now)
  • Metzeler Roadtec Z6 Interact (Sport Touring)
  • Metzeler Roadtec Z6 (Sport Touring)
  • Metzeler Roadtec Z4 (Sport Touring)
  • Michelin Pilot Road 2 (Sport Touring)
  • Pirelli Angel ST (Sport Touring)

Rear - Solution 6

Convert a Ducati 17 x 5.5 single sided wheel. I like this idea a lot. You have to be careful that you get the smaller bore Ducati wheels and then bore it to fit the Honda axle, install longer wheel pins and space the wheel a smidge to the right to correct the offset. All quite minor modifications to make. I'll get on this some day.

Rear - Solution 7

Convert to a 1990 to 1993 VFR750F wheel that is the desired 17 x 5.5. The 1994 to 1997 VFR wheels were 5" wide. They might also work if you don't mind a narrow wheel and a different spoke style. This always looked plausible to me, but sadly getting wheel information that is complete from anyone is difficult at best. Again, I’d love to have complete wheel and axle dimensions from a 1990 to 1993 VFR-F but unless I buy them myself this probably won’t materialize. I will go out on a limb and say that a modified RC30 axle and this wheel would work. Take that for what it’s worth, I haven’t done it. If you do go this route you would lose the single nut attachment. The offset is probably a bigger concern than attaching it to the RC30 axle. VFR wheels are held on with four lug nuts like a car. The 8 spoke pattern matches that of the original 18” RC30 item so it won't look too silly, even with lug nuts.

A similar option is to use a VFR800 wheel but sorry, again no real info. They are 17 x 5.5 and bolt on with 4 bolts also. No idea what offset they are, or what any clearances are like.

Rear - Solution 8

Use an RS250 Race wheel. These aren't too hard to find and aftermarket ones are available from Marvic and Marchesini et al, but the spokes are swept the wrong way as the RS wheels mount/dismount from the port side of the bike. It makes the bike look slightly retarded. These also have the same problem as any ex-race wheel when used with respect to damage, age etc. I wouldn’t waste my time on them if for no other reason than the clumsy look.

Rear - Solution 9

Use an NSR500V wheel in 17x5.75. It’s ¼” too wide and a magnesium ex-race wheel. I almost bought a minty one cheap and given the chance again I would, just to try it out.

Rear - Other solutions

Have an idea for a rear wheel solution? Contact Me and let me know about it. The 17 x 5.5 Delkevic wheel would have been perfect. What a shame.
POSSIBLE SOLUTIONS - FRONT WHEEL and TIRE
Front - Solution 1

This is so easy to fix most bikes have had it done already.

If you want a 3.5" wide wheel that matches the original in spoke design, hub width, offset, brake disk drilling then look no further than Honda. The following wheels are 17" x 3.5" cast aluminum and will bolt right on with zero modifications. It really is that easy.

1995 to 1997 Honda CBR600 F3
Honda VFR400R NC30 (and the RVF/NC35)
1994 to 1997 Honda VFR750F
Honda CBR400RR NC23
Honda RVF400R NC35

The only kicker with this solution is that everybody and their hyena wants these used wheels. It's not so much RC30 owners, but CBR900 owners trying to rid themselves of the 16" wheel they were cursed with. This also goes for the RC45 with it's 16" balloon tire. With some of the prices I've seen for questionable used front wheels people should save themselves the grief and buy a new 17 x 3.5  from Honda, or see Solution 2 for a low budget alternative.
Front - Solution 2

Very similar to Solution 1 except it's an aftermarket copy. Delkevic make this wheel in 17" x 3.5". They are, I'm told, Chinese made cast alloy, but the price is very inviting and I have never heard of a problem with them.

Click here to check out the Delkevic Wheel. They can also supply this wheel polished, but I'm not sure why anyone would actually want a chrome wheel.

Approximate prices (~2010~)
  • Delkevic New   $175 (polished for $240)
  • Honda Used     $100 to $250
  • Honda New      $600
This wheel is no longer manufactured.
Front - Solution 3

If you possess a Swiss specification RC30 the solution is simple. Don't do anything, they came with a 3.5" wide rim from Honda. This wheel is discontinued now.
Front - Other Solutions

These are numerous because of the similarity with the bikes mentioned in Solution 1. The world is your oyster here. Whatever front wheel you select always check the fit to your bike. Check clearances to fenders, fork lowers, and brake calipers. The brake rotors should be centered nicely in the calipers.

Here is a Honda made NC30 wheel.

Here is a Honda Made CBR600F3 Wheel.

The most important thing to consider when dealing with wheels and other drivetrain parts is safety. Never assume anything. The wheels and tires on your bike see pretty big loads and the attached tires are the only thing touching the ground, with any luck. Don't scrimp here. Buy cheap tank pads and windscreens, not driveline parts.
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