I am currently building a new 4-seater with a 2.5 subaru 350hp with a Mendeola 2D trans and 18" travel. It
should weigh about 1500-1600 lbs without passengers. We buggy at Little Sahara in Oklahoma which has lots of trails and small dunes. We make occasional trips to St. Anthony in Idaho ( wish it was closer). My current 2-seater buggy has 2000 STU's with the paddles cut at a 60/40 split to get float and traction on 18" wheels. This combo works great for my 2275 VW ( aprox 175hp) with a bus trans ( 4:86 Ring and Pinon). I Know i need to downsize my tires for the new buggy and have been looking at the X-treme 14.50 x15, STU Sr1's, STU blasters, STU 13+ ( same size as 14.5?). I am trying to keep it on a 12" wheel. So i think a 16.50 is too big?
Here are some of my concerns
1/ Are the smaller tires going to burry me when I get into a tight space at the bottom of a trail that I need to get out of ?
2/ Will the smaller tires work similar to my large tires since i have more HP and can get more tire spin?
3/ Now i can just power into the buggy on a hill and get the front end up. Will i get the same effect with the smaller tires??
We like to run trails and just general playing so sliding in the corners is important. Any knowledge on the subject will be greatly appreciated.

Thanks

If sliding the corners are important you need to buy flat profile tires. Those of us that have Funco Big5 four seaters run the Dune Sport tire from Sand Tires of America, about $325/ea. My car with Turbo Subaru 2.5L weighs 1550lbs and I use the 14.50X15 tire on 13" rims. 12" rims aren't wide enough to keep the profile flat enough. The flat profile of this tire provides an awesome feel in the corners, very predictable. You can pick #1 or #2 cut depending on if you want more spin or less. I believe the height of my tire is 30", so you can compare that to your tire to determine any ratio change and adjust it in your 2D build. Most trans builders will know what to provide you for ratios for that motor, weight, and tire size. If not PM me.

You'll get good flotation with the contact patch and added width of the Dune Sport, you'll like them. Take a look at the pictures in the Funco site, there are hundreds of pictures. Check out the tires, they ALL run the DuneSport because it has the best handling characteristics. V8 cars use the 16.50 width for more flotation of the additional engine weight.

By the way, the Subaru motor is going to blow you away compared to the VW, but 350HP may be too much for a stock EJ25 block, unless you're using an STI block, or a racing closed deck block. With a stock non-STI block you should try to keep the boost at 10lbs or less to prevent head gaskets from blowing. That's usually around 300HP.

Make sure you include a Funco or TransWerks nosecone kit in your budget to help the main bearing in the 2D transaxle.

Thanks for the info. I am going to use an 2.5 STI block with the 2.0 twin turbo heads i have been working with Jeremy and John at outback (outfront) they have the answers and a proven product. Eric at transworks has been giving me lots of help also. Are most of the cars out there running full width paddles? Most of the wheels ( bead locks) i have looked at are 12" or 14" wide who makes the 13" wide??

Yes, as the Funco pictures show, nobody cuts half the paddle off "width-wise". Frankly I've never heard of such a thing. The Dune Sport, along with most other paddle tires offer a #1 or #2 cut. Half the paddles are a little larger than the others, and you cut off the ones you don't want. But I have never heard of cutting paddles off so they are not the full width of the tire. I guess with VW motors that trick may be useful to get more wheel spin to make up for the lack of power, but you won't want that with the Subie motor.

Douglas made my 13" rims, with bead locks integrated. Yes, most folks run bead locks. 14" may work for you, but that made my car over 92" wide for trailering in an enclosed trailer. 12" is too skinny for the 14.50 tire.

Since you're working with Transwerks, make sure you buy their 2D nosecone and bearing kit when they build your transaxle.