Maximum Front Tire Width for Stock Rim 1st Gen?

Zeus36 · Jan 6, 2020

I'm looking to order a replacement for the stock Bridgestone Exedra G525 110/90-18 61V front tire. I don't run front or rear fenders as the bike has been stripped down to a Streetfighter look with the front forks dropped 2 inches. I currently run a Shinko 180 x 15 on the rear. This will be replaced with a 185/60-R15 radial car tire once it wears out and I will join the Darkside.

I'm looking to fit the widest front tire on my 1997 factory front rim. I've been pouring over the posts here and am getting several conflicting rim widths and tire fitments. Some say the front is 2.15 inches, some say 2.50 inches.

Comments have mentioned running a 130, 110, 100, and 120 on the front. I'm leaning towards either a 130/70-18 or 130/90-18 if a shop will mount it. (I guess I will need to find a shop when I convert the rear)
Has anyone run anything wider on a stock front wheel?

I don't ride in the rain, drag my knees or carve out the twisties. Mainly straight line hard acceleration from stoplights and 90-120 MPH (at 5 am) to and from work. This will be for appearance reasons and not riding performance. I've stopped riding on the weekends due to texters.

mabdcmb@yahoo.com · Jan 6, 2020

The OEM front wheel is 2.15 x 18
The info is in the service manual, Chapter 8, page 12.

I've run a 120 on mine with no issues.
There have been a few guys that put a 130 on. I think they are still alive... I'm sure lots of folks will say its not a good idea. Its not made for that narrow of a wheel.

Zeus36 · Jan 6, 2020

Thanks for the service manual reference. I do see it is listed on that page as: MT2.15 x 18. I looked up the MT designation and it is the rim contour type with a 5 degree tapered bead seat.

one2dmax · Jan 8, 2020

The motorcycle beads are not very conducive to "darkside" car tires usually. Some have done it though if you look up the beads you'll see that it won't full seat and could unseat. But, some people are hard headed like that. The narrow 3.5" wheel is also not very good for much more then the 170 tire but again I see guys doing what they want. Hell I see hispanic guys putting narrow tires on wide wheels so it must be ok lol.
The front is a 2.15" as you have found out. Not sure where you got any other info but probably from the same guys that say a car tire will fit just fine on a motorcycle rim without any modifications. The 110 is barely in the width range as it is. The 120's and 130's are way over pushing it but again do what you want. The ideal wheel size for a 130 would be in the 3.5" range. I do have a front only Carrozzeria (in black powdercoating) if you wanted that wider wheel (also ultra light). Haven't tried wider then that since that's all that will fit in a stock front fender (and it just barely does). You MIGHT be able to go a little wider (if they make something).

Fire-medic · Jan 10, 2020

Sean's points should be heeded.

If you look at any premium tire manufacturer's data on tires and wheels, they have wheel width and design (the 'metric' designation, by letter prefix) ranges vs tire size (carcass width and aspect ratio) ranges. As has been discussed repeatedly on here, especially in the 'Dark Side' threads, car tires belong on car wheels! Now, that's not going to stop anyone from running one, if they're that obstinate to value appearance over engineering principles. Try writing to the tire manufacturer's engineering dept. about using their product on the VMax wheel, be sure and include the metric wheel sizing, so they can be fully-informed. Let us know what they say.

OK, we all-know, they're going to say, "no." So, you're doing it anyway. Consider this: running a tire stretched beyond its design parameters is going to set that tire up for premature failure, This failure may occur suddenly. You may lose control. A wreck may ensue. What level of incapacity are you willing to endure for the 'streetfighter look?' A fractured arm? A fractured pelvis, or a fractured femur? Concussion?

I get it, bikes with fatty tires are 'cool.' But if you're going in that direction, use a wheel properly-sized and properly-designed for motorcycle use. Shod-it with tires which are designed for motorcycle use. You may need to widen your swingarm, and to buy a new front wheel. Do it to give yourself the greatest margin of safety possible.

Wide-carcass tires on narrow rims aren't allowing the bead to seat properly. The design of the laminations of plies is engineered to flex a certain amount, and to be able to do this for millions of revolutions. This creates heat, which needs to be spread-across the tire, so it doesn't overheat the rubber compound, which if the overheated rubber does happen, causes the 'greasy' release of chemicals in the rubber compound, and a loss of traction because of it. Encounter a patch of spilled diesel fuel, coolant, ATF, or plain-old motor oil at an intersection, and now add a left-turning motorist in-front of you: now you need all the traction and help you can get. The NHTSA has shown that the "11 o'clock" position (for the motorcycle rider) is a predominant point of origin for motorcycle accidents, i.e., someone turning left in-front of you as you enter an intersection. "But officer, I never-saw the motorcycle!"

If you're gonna exhibit your bike at a show, the fat car rubber and the oversized front tire outside of what your wheel was designed to safely-hold may get you the 'people's choice' award. Take that and your bike, push it back into your trailer, and swap-out your 'show wheels' for something that's designed for safe use, within engineers' parameters. Something which will give you the best chance of survival on the mean streets.