Tire advice

[sikbrik]

Goal = give this thing slightly more ground clearance so the kid can take it through the grass from time to time, when the driveway gets boring.

It's an older Italkart cadet with the 60cc IAME Parilla 2 stroke engine.

We dropped the rear axle down as low as it'll go, which raised the kart about 1/4". We'll be moving front spindle spacers to get maybe 3/8" up there, too. There's room for about 1.5" more tire height, which would get us another .75" in the air. Undecided as to whether that's easier by moving up to a 6" wheel or if I'll have options in a 5" tire, because we have about 10 or 12 spare 5" wheels. I feel like that .75" lift would be plenty for "around the yard fun". It's got 3 bolt hubs in the rear and I don't know (yet) what size spindle up front but it's a single "through wheel" setup with sealed bearings pressed into the wheel...5" wheels...is this all "standard" stuff?

Any recommendations on maybe an 11.5", 12" tall treaded tire which would possibly fit the existing 5" wheels? OR if anyone can point me to a good wheel/tire combo that won't break the bank, that'd be good, too.

Thank you!
Mike

 

[anderkart]

You'll need 6" diameter rims to install taller tires ranging from 12" to 15" tall.

You'll probably discover you'd also need to replace the axle sprocket to compensate the gear-ratio, when installing taller rear tires...

We could help you find 6" diameter rims and taller tires. But first you need to measure & post what bolt patern your karts rear rims have. You'll need to very carefully take all 3 of the measurements exactly like this pic shows:

 

[sikbrik]

I'm going to go with Metric because I came up with a measurement of 2" for A (which is darn close to 50mm) and 1-9/16" for B, also darn close to 1.5"/40mm. So that's the rear wheels.

The fronts I still need to figure out because they're just bearing mounted wheels, a large nut on the spindle holding them. It looks like I can convert that over to a more traditional hub with a similar bolt pattern to the rear.

The rear axle is 30mm, if it matters, in case there is any discussion of changing hubs. I only say that because a lot of the less expensive front hubs I've seen appear to be 17mm bearing with US pattern.

Thanks for any advice

 

[Joe-405]

I would go with what anderkart is saying. 6” wheels have a whole lot more options and tires will be cheaper also. As that is a more common size on regular stuff other than just race karts.

 

[anderkart]

I'm going to go with Metric because I came up with a measurement of 2" for A (which is darn close to 50mm) and 1-9/16" for B, also darn close to 1.5"/40mm. So that's the rear wheels.

The fronts I still need to figure out because they're just bearing mounted wheels, a large nut on the spindle holding them. It looks like I can convert that over to a more traditional hub with a similar bolt pattern to the rear.

The rear axle is 30mm, if it matters, in case there is any discussion of changing hubs. I only say that because a lot of the less expensive front hubs I've seen appear to be 17mm bearing with US pattern.

Thanks for any advice

Douglas, Burris or Williams are the 3 most common brands of racekart rims. I know at least one (if not all) of those company's make 6" diameter rims to fit your metric rear hubs, and also 17mm/spindle-mount rims. But online racekart shops in the USA don't list these metric rims on their websites, because hardly anyone in the USA runs 6" diameter rims on their metric race karts...

But some of the metric Race karts and Super Karts that race in Europe, do use these 6" diameter rims...

So... you'd simply need to call and special order those metric/6" diameter rims from any of the knowledgeable on-line racekart shops in the USA, like this one: http://out2win.com/contact.html

 

[sikbrik]

Special order got me nervous about money so I found these. I never did come back and mention it's on 10x4.50/5 tires now.

12x4.00-5 Quenda knobbies. $160 for 4 with tubes. I've got a bunch of spare 5" wheels. Wondering if that extra inch of lift might be enough.

If it looks like it will, it has a 10 tooth clutch and 82 tooth sprocket on it now...would it make sense to try to go bigger/more teeth?

 

[anderkart]

Special order got me nervous about money so I found these. I never did come back and mention it's on 10x4.50/5 tires now.

12x4.00-5 Quenda knobbies. $160 for 4 with tubes. I've got a bunch of spare 5" wheels. Wondering if that extra inch of lift might be enough.

If it looks like it will, it has a 10 tooth clutch and 82 tooth sprocket on it now...would it make sense to try to go bigger/more teeth?

You'd only be gaining around 1-inch of additional ground clearance with those tires, and that's assuming they end up being as tall as their advertised size. Because sometimes tires end up being shorter than their advertised hight after being installed on the rim, especially if the rim is wider than the tire ...

Those 12x4.00-5 tires would probably fit on your front rims fine, but you might discover your old rear rims are a bit too wide for them. That size of tires are probably designed to work best on rims that are between 3 to 5 inches wide...

___________

You could probably locate and buy a set of four, 6" diameter Used-rims for $10 each (plus like $20 more for shipping) from the classified section this gokart website: https://karting.4cycle.com/forumdisplay.php?19-Classifieds

You could search through their older for sale ads, and then also post your own new ad (for free) asking if anyone has a pair of used 6-inch diameter racekart rims with the Metric 3-bolt patern (for the rear of your kart), plus another pair of the 17mm/Metric-Spindle Mount variety of front 6" diameter rims for sale.

Then you could install 15" tall Turf Saver tires that would actually give you enough additional ground clearance to make it all worthwhile doing... You'd need those rims to be anywhere between 5" & 7" wide to correctly fit 15 x 6.00 - 6" Turf saver tires.

We'll help you figure out your new gear ratio options,
after you decide on what size tires you'll be installing

 

[sikbrik]

That sounds like a good plan. Thanks!

 

[anderkart]

Your welcome...

Another source for purchasing used 6" diameter rims would be checking out all of your local gokart racetracks. Most tracks have a website, with a classified section. You could check out those websites, and also post your own 'Wanted-Ad' asking if anyone wants to sell the exact rims you need. You could also post Wanted ads in all of your areas craigslist, that you'd be willing to drive to for a bargain.

Lots of kart racers replace their tires and rims often. Sometimes the rims are damaged, but the good-used rims (with or without tires) typically get sold off for around $10-$20 each...

Here's a link to a website that lists (just) some of the kart racing tracks/websites in your area:
https://www.worldkarting.com/tracks/

You could also preform a google-search, to probably find a lot more kart racing tracks/websites in your area...

_____________
While your searching, just keep in mind that 6" diameter rims are only/typically used on Oval-racekarts in the USA. These Oval karts typically go by the generic term as being an Off-set chassis, LTO-kart, Or an Offset-chassis.

The variety of racekarts that compete on tracks with right & left corners, are called Strait-Rail, Cadet-kart/Kid-kart, Sprint kart, or Shiftier-racekarts; And the strictly enforced track-rules all of those variety's of racekarts, typically require them to use 5" diameter rims, not 6"...

I've know'n a lot of guys that raced different karts at both of these types of tracks, but you should probably start out by concentrating your used Rim-search at the oval-kart websites. Or better yet, go visit those tracks in person on a race night and buy a pit pass, so you could go down into the pits and ask all the drivers if they have any of the rims you need for sale. I'll bet some of them will...

 

[sikbrik]

Heading to Gettysburg this Saturday night for a dirt oval kart race!

Meanwhile I also scored a set of used custom hubs and redrilled 6" wheels (6x6.5 rear and 6x6 front) via the suggested want ad, from a really nice and helpful racer/builder.

15" tire selection is next! Maybe I can find used but even new ones seem pretty reasonable.

 

[anderkart]

Cool, good job man.

Your kart will probably end up with a sharper-turning ability using the 13" tall tires, over the 15" tall option. Because the 15" tires will probably contact the frame and/or front bumper sooner while attempting to make sharp turns.

I'd suggest test-installing those front hubs and rims (with the valve-stems pointing outward) before buying any tires. You'll probably need to use your front wheel Spacers to position the hubs outward as far as possible, but maybe not. Then you could turn the karts steering wheel to each extreme direction, and use a tape measure to help estimate the 13" & 15" tire height's... To help decide if you want to purchase the 13" or 15" tall tires. Keep in mind that the sidewalls of these tires will most-likely pooch out an inch or 2 further than the 6" of tread width...

Your local Wallmart will probably have those 13' & 15" Turf-Saver tires in stock, and priced about as low as anywhere else... They'd probably even install them on your rims, if desired too. Have them install new valve stems too, they're fairly inexpensive and It'd be a real bummer if your old ones ended up leaking at the rim-seal...

I wouldn't mess around with used Turf saver tires, guy's don't typicly remove them from their riding lawn mowers, unless there's something seriously wrong with them... The rubber in used tires will also of hardened over time, and they'll probably be much more difficult to install on the rims &/or to set the bead while Inflating.

Measure carefully and spend a little more now on a nice set of brand new tires, and you'll end up saving money in the long run...

 

[sikbrik]

Just a quick update...got the wheels and hubs today. All looks great. I need to give a shout out to Bill Hamble at 2nd II None Racing - great deal and took the time to understand my need and make something work out without breaking the bank.

Okay, next weekend, tire shopping and figuring out how to post pics.

 

[anderkart]

You'll find a thread with pic posting instructions near the top of the 'Photo Gallery & Project Log' section of this forum.

 

[sikbrik]

Update; wheel clearances with up to a 15x6 tire look good. We have to remove the rear bumper and side body panels (or trim them) but the frame itself has no issues.

Ride height with 13" seems like he may still have some issues with ruts and roots but I only had 1 to play with and it's tough to tell. 15" seems a little tall, again subjectively with only 2 mocked up on the ground.
Those are the 2 sizes I had to compare on the kart...so I'm thinking about splitting the difference with the Carlisle knobby 145/70-6 (~14") tires all around. Thoughts? He'll have right around 3" of ground clearance.

We're currently running a 79 tooth sprocket with 10 tooth clutch and it's got good top speed but I'd rather gear for a bit more torque in this new combo if we go this route. I have an 82 tooth sitting around but thinking I need to get up into the 90s. Off to run some math but open to ratio and/or tooth recommendations. Thanks!

 

[Nosandwich]

The 145/70's aren't going to be 14" tall, somewhere between 13 and 14, and maybe only 13.5". So...it's somewhat shy of a 1/2" gain.

 

[sikbrik]

Thanks, nosandwich. It's a 10" tire on there now (I was wrong about the 11") so the 1.5" additional clearance would be good but probably still better with a 14.5" or 15" tire for the property we run on. Thinking of abandoning the project for a bit because I've realized I'm going to need a jackshaft setup to make it practical to run off-road gearing for the 2-cycle with big tires. Right now it's a 7.8:1 ratio topping out at around 40mph. I want to get to at least a 12.5:1 ratio and I don't think there's a 125 tooth gear out there. Even if there is, I've seen charts saying 2 stroke hilly off road should be over 20:1 for proper torque. It may be simpler (cheaper) to just have 2 karts for either purpose or wait for the jackshaft when I do either a 4 stroke or electric conversion down the road. I don't expect this little angry 12000 rpm bumblebee to last forever.

 

[anderkart]

Have you already checked out the Burris Jackshafts for racekarts: http://www.burrisracing.com/main.html
They're pricey new, but you might find a good used one you could mod to work for your situation.


Here's another option to consider: https://www.bmikarts.com/Clutch-Mount-with-Jackshaft_p_1129.html

 

[sikbrik]

Thanks, anderkart... I'll probably start a new thread in drivetrain, then. I think I'll do the 15" tires just to be certain it's high enough, since I need gear reduction anyway. I want to have a dual-purpose jackshaft, I think...one large gear for off road and one 10 tooth so I can loosen the collars and make it back into a 10" tire street kart.

This looks interesting: https://www.bmikarts.com/2-Cycle-JackshaftMotor-Mount_p_1118.html

Of course, part of me says do a 4 stroke mount with the predator swap and do the jackshaft anyway, along with a TC. Decisions decisions... it's taking time and money from my Volvo 240 wagon cart-hauler project but it's currently more fun because I get to see the smile on my boy's face.

 

[anderkart]

Your welcome. ~ You might discover your kart needs a jackshaft to install a 4-cycle engine anyway. The output shaft of 4-cycle engines are on the opposite side of your 2-cycle engine...

I haven't seen pics of your kart yet to confirm things, but some racekart chassis are designed for 2-cycle engines only: They typically don't have a Keyway machined into the axle, where its needed to install the sprocket inside of the axle bearings, like this pic.

And some (2-cycle only) frames also have an angled rear-cross-member, that don't leave enough room for installing a suitable (8"-10") diameter sprocket in this location:

 

[anderkart]

If your axle and/or frame is not designed for installing a 4-cycle engine, a jackshaft could be used for a setup similar to this pic:

This racekart has a 4-cycle engine with a Burris (brand) 15-degree motor mount, with a built in Jackshaft: