Motorcycle Tire Sizing Question
 

I wanted to replace the old 4.00x18 rear tire on my recent purchase of a Yamaha DT400. I ordered a Dunlop D803 Rear Trials Tire from Power Sport Superstore to match the new Dunlop D803f 2.75x21 Trials front tire which the previous owner installed.

What I received is a 120/100 x 18 D803GP Trials tire. I looked online at various charts and it appears that the tire I received is best suited for a 5.00 - 5.10" rim. Best suited tire for my 4.00" rim, apparently, is 100/90 or 100/100x18.

I called Power Sport Superstore and spoke with two gents who had no information for me other than to call Dunlop.

BTW, I will only be using the bike for street riding - no dirt.
If this new 120/100 x 18 will fit fine w/o issues, then I'll put it on.
Otherwise, Power Sport Superstore will email a RMA label for return on their dime.

Any assistance y'all have would be greatly appreciated regarding the fitment, pinch angle, too much additional weight, etc.

I think it's too large. I run a 150 race tire on one of my bikes that specs 140, but you're talking 2 sizes. Too much, imho.

I think so, too. I also think that they sent me this tire just to be sending a tire to sell.
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Just called Power Sport Superstore to get a refund label.
What's up with the youth of today? Snotty-ass punk working customer service. Oh well.

There are a few handy conversion charts out there that can help. I grew up with inch sized tires, so I'm always wondering "how big is that?" when I'm buying in metric sizes.

Here is one on the Maxxis website:

Motorcycle Tire School | Maxxis Tires USA

It does look like what they sold you is way too big.

That's a really poor choice for a tire to be used on the road. If you intend to only ride on the street, do yourself a favor and buy a pair of street tires.

Just to be clear, I'm saying that tires suited for use on a trials bike are not optimum for higher speeds on pavement.

JR

Mounting that tire on your 4" rim will make it 'bow' in from the corner tread making it less effective than if the proper size tire were used

Thanks gents.
I was just trying to cheaply fit a new matching rear - front is a new Dunlop D803 Trials...previous owner.
But I've always wanted to try out the Pirelli Scorpion MT 90/AT...so I'll get a set of them, methinks.
Pirelli has a 20/40 deal on now - $40 credit card on qualifying tires.
A set will cost me around $186 to my door - minus $40
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110/80-18 rear......
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http://forums.pelicanparts.com/uploa...1457462265.jpg

That Pirelli still doesn,t look like a tire best suited to street riding only. might be a good dual purpose tire though

They're going on a '75 Yamaha DT400 Enduro that I'm restoring...staying with the spirit of the bike.
Taking off the knobbies...my dirt days are over.