Any input on either of these running a 245/40? Current running a 15x9 upfront on a 225 RC1. I'm limited to a measured 257mm in NASA TT5, thinking 245 on a 9.5" wide is going to be the best route.

Really don't want to 5 lug swap the front, but I'll probably have to if I want to go 17x9.5 as I don't see a 4x100 out there in a decent track wheel. Plenty of 17x10 options, which I would do if I wasn't restrained to staying under 257mm measured.

I'm guessing I'll need to space out my fenders(not much info out there on doing that either, but looks straight forward I guess)

 

all the cars i know running a 245 are K swapped. that being said... with NASA rules they are all on 15s... with GLTC rules they are on 17s.

 

Yeah.
I'm K swapped. I think a 17x9.5 with 245 is going to be the quickest option within the rules. Which would mean 5 lug the front and change the FD since I'm still on a 4.3 a2 trans.

I'm assuming the NASA guys on 15's are HC cars, which isn't a thing where I'm at. So for TT5 my only restriction is the 257mm at my weight.

Be nice to find some info out there on spacing the fenders before going at it blind. But I'm sure it'll be needed.

 

They are all ST4 (super touring... aligning with TT rules wise) cars that were initially built for Honda Challenge H1 class.... @Dublocivic has 17s on his car and is relatively fast and is shooting for tt4 or tt5... so bother him and see what he thinks.

I believe this was done to keep the geometry in a better zone without having to do major chassis modifications like Kutil has done to his sedan.

you really need to settle on the wheel setup before you get into the transmission... IMHO you will want a FD/plate diff and the DC5R 4/5/6 in the car.

 

Thanks.

Yeah, I think I'll finally bite the bullet and go 17s. I've got a Mfactory helical in the car, with a clutch diff waiting to go in.

17x9s/17x8 might be OK, though a 9.5" is going to be more ideal, but that will require a 5 lug conversion.

The car is mostly full interior with AC, it's around 1.5-2.5(around 2 minute laps) seconds off the track records at the various layouts. So it's not far off pace, as long as I do my part.

Appreciate the input.

 

Some one might save the day with a 17x9.5 4x100 ET40. Hopefully right around end of Jan early Feb 2024

 

I need to come back here more often. to catch up with posts.. So I have a 17x9 up front and a 16x8 in the rear (about the same overall diameter w/tire). I kept the 16s for rears because why not.. they work just fine and may as well use up the tires. 255/40/17F and 225/45/16R. Fronts are spaced 10 or 15mm on an ET45 Hypergram, spaced the bottom of the fender out about an inch and rolled the fenders a smidge past flush and compression/camber in it clears perfectly. 30mm wider track up front changed some stuff but once you get used to it, its faster.

 

Thanks for the info.

Going to try the 17x9.5s upfront with 235s or 245s depending on if I run Maxxis or Toyos. I'll update the thread with what I had to do for fitment.

 

Would love to see pics of what you had to do to the inner fender and how much bump travel you have as a result.

 

The inside of the arch, everything is rolled flat. I don't run fender liners or anything, the tires absolutely rub at full lock on the frame rails. The top is pulled out as far as it will go, you could even slot the top bolt holes and grind the upper pinch weld, reweld and smooth that out to give you more clearance and slide the fender outward more. I haven't needed to do that yet, I just used an Eastwood fender roller and did a **** job but they do clear. Ill see if I can get some pics. For reference, I am on the PCI spherical UCAs running max camber, the tire does have some contact under "gator compression" occasionally, but not under lateral G-loads. No contact with the UCA/body at all.

 

So the top of the tire doesn’t hit the body just from the larger diameter? And you still have pretty good bump travel from your ride height without massive bump stop spacers? That’s great to hear. I plan on experimenting with some 255/40R17s on my Integra this spring.

 

I hear these wheels are about 2 weeks out!!

 

I just got an email that the 17x9.5 4x100 ET40 are now in stock. Only in one color for now though.

 

949 racing has 17x9 6ul's if you're interested in those.