tire size question

Hey guys, I need a little help. The rear tire on my xj550 Seca is getting near the end of its life. Now I don't know anything about motorcycle tires. Does anybody know the widest tire I can mount on the stock rear rim? Any help would be great. Thanks

 

I don't want you to take this personally. You don't know what you just walked into ( only 4 posts in here - how many miles on a bike?)...

Ok - first - I'll ask why do you want to know what the largest tire you can use is? I'll guess that it's either looks or perceived performance.

On the looks front I'd gentally chastice you... what looks good doesn't have to work well.

On the performance front I'd suggest that it is a trade off - it's not as simple as saying a larger tire gives a larger foot print which is better for extreme lean angles, braking, and putting the power to the ground.

On a big hp bike you need a large tire to get the power to the ground. On the 650 you don't, you certainly don't need it on the 550.

So - the question of lean angles - I've never had a problem with the stock sizes, infact, to push the tire to the limits while riding properly you have to ride EXTREMELY fast... I've melted the stock tires and still had traction left. So I don't think you need the extra width for safety.

The next thing is flixability - on these bikes the stock tire helps it get over - making it wider is going to make it slower... as it is the xj's are no supersport so I wouldn't want to loose any more of the turn in speed.

The other tiny thing is that a larger tire weighs more - slowing down acceleration.

The next thing is price - a larger tire will cost more.

This is more important:
A wider tire might not fit the rim properly. In all likelihood it will be pinched. This will change the profile of the tire - usually making it more rounded. Basically - you'll find that you can't use the edge of the tire and that the center will get eaten by the highway. This is a best case scenario - the worst case is that it could fail in some other stange and wonderful way. A pinched tire doesn't behave the way the manufacture intended it to function... so they can't predict what will happen.

So - I'd stick with a stock size UNLESS you have some specific reason to change tire size that you understand and accept the side effects of.

NOW - to temper that - On the xj650 many people run a 120, I run a 130-90-16. I'm almost certain that the stock size (maxim) is 130-90-16... the smaller tire would help the turn in...

Anyhow - seriously consider what you want from the tire and weigh the options up... if it's just that you wanted a bigger tire because it looked better or you thought it might help the performance then I'd suggest finding a better quality stock sized tire.

Cheers,
woot.

 

When I was racing my Seca 550, I was running a 120 rear and a 100 front. I raced at Willow Springs and you are leaned over on the right side for a long time. I never ran out of tire, ran out of track once but that's a different story I tried the 130 but traction actually seemed a bit less and felt alot different.
LOL I am right up the 91 from you. If you want to go for a ride let me know
Sean

 

Woot, thanks for the info. The reason I asked was the tire that is on there now (I believe) is smaller than stock. From a little poking around I did online I think the stock tire size is 130-90-16, but I may be wrong. Theres a 110(?) I think on there now if I remember correctly. I'm going to need to replace it soon. The reason I wanted to know the widest tire was 2 fold - 1 being looks (that rear tire looks so dinky) and 2 being performance/stability (more meat = more traction...or so I thought). Like I said, I don't know anything about motorcycle tires. Figured the same principles apply to MC tires as to cars tires. As for lean angles and whatnot, I don't ride that hard and I'm not accelerating like a bat out of hell. As for price, I'm not that worried about price as long as I'm getting the right tire for my needs.

 

Realistically a 120-80/18 is going to be the best for the rear. If you look at the profile of the 120 tire and the profile of the 130 tire they look similar. The similarities end when you pinch them with your rim. The 120 will stay somewhat the same, the 130 will get more rounded. When the tire gets more rounded the contact patch of the tire to the ground gets smaller which isnt what you want. It winds up being extra weight and when every ounce counts and its not a benefit then it goes.
You have a 130-90/16 for a rear, are you sure its a seca and not a maxim model???

 

Me? I have a maxim 650 - 81... stock IIRC is 130-90-16... the 550 IIRC was 120... as were some of the seca's (with ?17"? rims)


I should verify that of course... 120 is what this fella needs.

 

I'm sorry, just checked it again - 120/70-18 on the rear now. Guess I just stick with the same. Thanks.

 

seca's r 18's wootnot! :roll:

i got a 18 as per manual and am happy w/it!

 

xj650rseca -
um - you had to get an 18" for an 18" rim

good to know the seca rim sizes - thanks for the bit of info folks

Cheers,
woot

 

i just poped in to read this thread and though id throw in a little i learned for outher people wanting a big back tire i wanted it for preformance and sat back and thought what i would gain when you ture more of your tire is tuching the road now if you sliding i can say a bigger tire with out changed more than just tire because the tire that would be tuching the road would not change. so the i guess you could do it for look's and that's about it. now for thouse of you who drag race with bikes a bigger tire will once agin do you no good due to when you lanuch off the line the more traction will just help the front tire come off the ground quicker creating more drag and slowing you down but yes you can ride the clutch till you get up to speed and it helps preven spining the back tire. or to sum it up quicker putting the bigger tire on makes it more round wich in some cases make less rubber tuch the ground when you are going straight bigger rim is an option but a lot of faburcating would be needed and theirs all redy a post on that so i wont go there sory if this is usless info but a bit of info i got from tire componies and some profession bike dragracers

 

I'm reviving this old post.

I also have a Seca 550 (81 with a chain drive) and looked and it said 110. I've done a bit of research on the topic of motorcycle tires and it seems wider is not always better, especially with a bike like a 550 Seca.

110...Is that smaller than stock on my bike? I notice most people have either 120's or 130's.

 

On an XJ550R Seca, the closest metric equivalent of the 3.00-H19 front tire is the 90/90H-19. For the rear the stock size is 110/90H-18. Most of the info sources I have found recommend not going wider than stock on the rear as the wheel is only 2.15" wide and will tend to pinch 120 and larger widths. On the front 1.85" wide wheel I have seen mention that 100/90H-19 should work fairly well also.

Avon has both the stock sizes in their AM26 Roadrider line. I have just installed these and from the few test hops I have done while troubleshooting the brakes and carbs, so far they seem quite nice. Bear in mind though these have been extremely limited test runs up and down the street. I have not run them more than 10 miles so far. So your results may vary.

 

Alright, so 110 is stock. Good. I'll keep it at 110 then. Thanks!