TSW is selling Mak Sonic (7-spoke) 18" by 8" rims on special for $129.00 each. I'm thinking about getting a set and mounting 245/40/18 Kuhmo Ecstas on them. Tirerack sells the Kuhmos for $125.00 each.

Whatcha think?

 

Can you post a picture of it?

 

Here you go.

 

those rims look hot! Plus, at $129 a piece, they look even better

 

Make sure they're not too heavy... otherwise, go for it!

 

That could be a problem. TSW said the Mak wheels are well made, but they aren't very light. How heavy should I be willing to go, Kev?

 

but they kinda look like the stock 17 x 7's ... no?

nothing fancy .. but for $129 .. that's pretty good! would u post what they weigh?

btw .. what do our stock 17 x 7's weigh?

 

IMO, stay somewhere close to 25 lbs.

 

I'll call TSW tomorrow and ask them how much the Maks weigh.

I'm also curious to know how heavy our stock rims are. Has anyone ever weighed them?

 

I say around 20 lbs or so would be great

 

The wheels weigh 28.75 lbs each. Is that too heavy?

 

Man those rims are fly.. they've got the Audi/VW look... a little more refind than typical ricer rims. They'd look great on a max IMHO.

 

Wow! That's pretty heavy! My 18X7.5 Tantrums are 23.2 lbs/ea and the 18X8s are only 24.9 lbs/ea. I guess you're going to have to weigh the pros and cons and go from there. The price is great though.

 

That's a tad on the high side.

 

Thanks for the feedback. I think I'll hold off for the time being. I'm not in a big hurry to make a decision and they have 60 of the 18" X 8" rims in stock!

BTW, Dave Burnette at Southpoint Nissan has a set of used SE 17" Rims for $900.00. Give him a call at (888)254-6060 if you're interested.

 

will getting 17 pound 18 inch tires give you an increase in acceleration? Or what?

 

The amount of torque that is needed for a car to accelerate is dependent on the size and weight of the rim. Basically, it comes down to the rotational inertia of the wheel + tire combination. If we assume that the wheel is simply a ring with all the mass on the edge, the rotational inertia is I = mr^2. If the mass or radius goes up, so does the rotational inertia. The equation for torque is tau = I * alpha. If I increases, then tau(torque) must increase to reach a given angular acceleration (alpha). So the smaller and lighter the rim, the better. That is why 15" steel rims are better for drag racing than heavy 18" alloys.

 

Interesting formula for rotational inertia. I thought I'd enter your equation into a spreadsheet and then set as a baseline a 16" rim (8" radius) with a weight of 25 pounds. I then increased the rim diameter an inch at a time and determined how much the rim weight would have to decrease to maintain approximately the same rotational inertia as that generated by the 16" rim. For a 17" rim, the weight would have to come down to around 22.5 pounds. For an 18" rim, it would have to come down to around 20 pounds. And for a 19" rim, it would have to come down to around 18 pounds. Unfortunately, the rim weight tends to increase rather than decrease as the diameter increases. So it really is important to keep an eye on rim weight when upsizing.

I also worked the formula in reverse. The 18" TSW rims I was considering weigh 28.75 pounds. If I wanted to maintain the same rotational inertia with my stock 17" rims, how much would they have to weight. The answer came back 32.5 pounds. I haven't weighed my rims, but I suspect they weigh less than 32.5 pounds. So if I upsized to the TSW's, I'd probably be increasing my rotational inertia substantially.

 

Cool.....nice work. However, the equation I had for rotational inertia, m*r^2 is a bit too simplistic. It assumes that all the weight is at the edge of the rim. In actuality, the wheel is more like a cylinder that has a weight distribution inside also (the spokes). So, to get a real measure, you would have to do a lot of measurements and do some integral calculus to get the true inertia. But, just for comparison purposes, it should give you a nice relative measure. As the more mass is located closer to the axis of rotation (the axle) the inertia will go down. By making the assumption we are, this gives us a bit of a worst case where all the mss is at the edge.

 

I dont think for anyone one of us that aint TRULY RACING, wheel weight dont matter. Most of the rims nowadays are all Alloy. The weight maybe plus or minus I say 4lbs max on any rim.

The extra rim weight aint gonna really matter on a MAX that aint trying to get .05 sec off the clock on a 0-1/4mile run.

Just what I know from hardcore racing, back in the days 2yrs ago

Dixit

 

Well, I decided to calculate how much power will it take to wind up a set of 16" (25 lb) wheels to 60 mph in 6.7 sec. It appears to be 1.34 hp.

Next step--a set of 20" (40 lb) wheels. It will take 3.34 hp to wind 'em up to the same speed.

Bottom line: an upgrade from 16" 25 lb rims to 20" 40 lb rims will "tax" your engine about 2 hp during hard 0-60 acceleration. Will it matter? I didn't try to check that out yet

--just my 2 cents

 

Interesting math, Kostya. By the way, I've been watching the TSW web site. Looks like two sets of 18" x 8" Mac Sonics were sold since I put up this post. I wonder if our guys bought either set?

 

I think stock 17"s are good enough for me. I have about 13.5k on my Max so hopefully I won't have to worry about the weels for another 20k miles.

I did the math just out of curiosity. Let me know if you need the Excell file I set up.