tire question for tire guru's like norcal.

silverstar · 01-08-2010, 10:01 PM

I am hopefully ordering my RC 3" lift in a week or two (as soon as my 4 wheeler sells). I was set on either the kumho kl71's, in 35x12.50 or more than likely the toyo m/t's in 285/75-18 due to both of these tires being narrower than a 12.50 tire(the kumho is not a true 12.50 tire). Both of these selections are really expensive and I just found out I can get a good deal (by a few hundred less than the other two) on a set of the firestone destination m/t's. The only problem is that the only 35" tire they make for an 18" wheel is a 325/65-18 which is wider than 12.5". I have seen pics of the RC UCA's barely clearing the 11.5" tires where the balljoint mounts. Do you think I could clear a set of 325/65-18's with the RC UCA's mounted on stock 18" SE wheels? I know, I know, go with prg!! The only problem is is that I can't swing the prg UCA's right now and I've heard many good reviews about the RC lift which is MUCH cheaper and in my budget. I'm doing the RC up front and a 1" block in the rear to keep it from sitting bulldog. Thanks for any help guys. adlk posted pics of how close the UCA's are to the sidewall of the Kumho's in his one post about the RC lift.

Oh and even though they're not as "exotic" as the toyo's or kumho's I have read many, many great reviews on the new destination m/t's as far as being a very quiet and long lasting M/T tire. They were actually my main pick before I decided to go with 35's instead of 33's.

**AZPRO4X** · 01-09-2010, 12:25 PM

As you saw in those pictures i posted it will be close for sure. If you can do a test fit thats what i would recommend, my tire shop only charged me $20 to do a test fit and when i bought the tires a few weeks later they took it off the price.

silverstar · 01-09-2010, 12:49 PM

I don't think i'll be able to do that because the firestone store doesn't keep that size in stock so they'd have to order them.

NorCal 4x4 · 01-09-2010, 01:20 PM

The KL71's are only 11.4" wide at the section width, (measured on a 10" rim), and a OEM 8" width rim is a measured 9" width. BFG states that a narrower rim pulls in a tires width by about 0.2" for every 1/2" narrower of a rim, so that would be 10.6" wide on an 8" rim. So, [10.6 - 9" = (1.6"/2) = 0.8"]
The KL71 35x12.5R18 tires should hang over both the inside and outside edge by about 0.8" ... about 3/4" to 1".

I saw the pic too, and you're right, not a lot of clearance. I do forget if he was running stock rims, or maybe they were aftermarket with a higher backspacing ... tucking them in.

The RC site suggests 33s ... maybe that is why they do.
Btw, buy some longer bumpstops, (for compression, not the droop). Looks like RC only tried to addressed the droop issue, and ignored the possibility of having your shocks bottom out. PRG says that the OEM bumpstops are o.k. with his 1.5" level kit, but provides longer ones with his 2" and 2.5" kits.

The LT285/75R18 Toyo M/T is 11.6 on a 8" measuring rim, so would hang over each edge of the rim by about 1/2" more, than the KL71 in the 35x12.5. So 1.3" past the edge for the Toyo.

The LT325/65R18 Firestone M/T is 13" wide on a 12" measuring rim, and designed for a 9" (10" measured rim as it's approved minimum).
But if the BFG rule of thumb applies when squeezing the tire down to a rim 4" smaller, then that would be 0.2 x 8 (eight 1/2" changes), = 1.6".
13 - 1.6 = 11.4" and so the sidewall would stick out about 1.2" past the rim. But the tread of this tire is more than likely much wider than either of the above tires and so would more likely rub, and since the RC UCA clearance issue was at the shoulder of the tire IIRC, this would probably not be a good choice.

The new Nitto Trail Grappler M/T in a LT295/70R18 is 34.6 x 11.73 on an 8.5" measuring rims so would be about 11.5" on the OEM. Probably somewhat less $ the the Toyo, and basically the same tire ... Nitto and Toyo are the same basic company, and share some of their production and casings. Trail Grapplers They should stick out about 1.25" past the rims. These are also less expensive than the 325/65R18 Firestone M/T's they have at at Tirerack, especially since they charge for shipping, but Discounttiredirect's price includes shipping!

For an 18" M/T I'd probably get the LT295 Nitto, and look for a used PRG, Total Chaos, or Camburg UCA. Also, the level spacer on the RC kit is only a 2.5" according to someone that measure one ... 1.5" measured, not the 1.8" for the 3" they claim. idk

**AZPRO4X** · 01-09-2010, 02:04 PM

Yes my KL71's are on factory rims. You could see if they have the same size and type but a different brand in stock that might help ?

silverstar · 01-09-2010, 05:34 PM

Norcal you are the tire guru for sure! Thanks for your tire math and input. I'm probably just gonna go with the toyos I guess. I really doubt ill find any used prg arms for sale. Maybe ill just go with a prg 2" mini lift then and keep my stock uca`s for the extra tire clearance? I'm sure with a 2" on an 08 I'd have to grind the coil bucket a little but at least I could run a wider tire. I've seen other 08 guys run a mini lift and squeeze 35's. Maybe ill just go that route. Thanks for all the help though and what's your thoughts on just going with a prg mini lift over the RC lift? Thanks.

NorCal 4x4 · 01-09-2010, 06:10 PM

Quote:

Originally Posted by silverstar

Norcal you are the tire guru for sure! Thanks for your tire math and input. I'm probably just gonna go with the toyos I guess. I really doubt ill find any used prg arms for sale. Maybe ill just go with a prg 2" mini lift then and keep my stock uca`s for the extra tire clearance? I'm sure with a 2" on an 08 I'd have to grind the coil bucket a little but at least I could run a wider tire. I've seen other 08 guys run a mini lift and squeeze 35's. Maybe ill just go that route. Thanks for all the help though and what's your thoughts on just going with a prg mini lift over the RC lift? Thanks.

I'd go for the 1.5" PRG level kit, since you have the longer coils. That way in case you upgrade to the slightly longer Bilsteins 5100's or HD's, you won't get too much coil bucket contact to compensate for with bucket trimming, (which you may need at that time). There would be plenty of inner clearance with stock wheels, but maybe a little of the pinch weld mod needed for the taller 35's.

silverstar · 01-09-2010, 11:25 PM

So I would have enough inner clearance to run the 325's on stock wheels? And I know I can clear 35s with the prg mini lift and the PWM so I may just go that route then. And actually with the deal I can get if I go with the firestones ill have enough to get the front 5100's. Then maybe down the road I can get the rear 5100's too. Or should I wait until I can do all 4 at once? Thanks again norcal. I looked at the new trail grapplers and the tread really didn't impress me.

NorCal 4x4 · 01-10-2010, 01:56 AM

Quote:

Originally Posted by silverstar

So I would have enough inner clearance to run the 325's on stock wheels? And I know I can clear 35s with the prg mini lift and the PWM so I may just go that route then. And actually with the deal I can get if I go with the firestones ill have enough to get the front 5100's. Then maybe down the road I can get the rear 5100's too. Or should I wait until I can do all 4 at once? Thanks again norcal. I looked at the new trail grapplers and the tread really didn't impress me.

I'd get the front 5100s ASAP. Things change ... there have been guys on here waiting to buy them for months due to a world wide back order, which should be about over now. My first mod was just rear Bilsteins from PRG, and I was amazed at the improvement ... made the Titan feel like it was on rails, and eliminated the wheel hop I used to get on one curve, that had a big bump, with broken pavement.

The Trail Grappler tread looks a bit flat, but now I always get aftermarket siping, which is cut in and provides hundreds, or thousands more edges than the molded in, so called siping the manufacturers provide. But if you don't like their look though, that won't change.

Yes on the inner clearance of 325's and stock wheels, and stock UCA.

Until the RC UCA, I think the only thing that Titan owners had to worry about, (inner clearance-wise anyway), with stock rims and 325's were the CST spindles that came with their bracket lift kits, (Greg at PRGproducts warned everyone about this in the sticky in the suspension forum), and the 2wd CST 4" spindle lifts. [The CST 4" spindles are worth this limitation for the 2wd Titans].

Since the 325s are technically too wide for an 8" rim, their maximum load capacity will be less, but that should not matter for a 1/2 ton. Any tread wear warranty would also likely be voided. Also if you keep the air at 35 to 40 psi, the load capacity will actually be less than the OEM passenger rated tires that came with the Titan, (at their 35 psi max), but the center won't wear out as fast by keeping the pressure on the low side, (since the sides are pulled in by the narrow rim). But if you carry heavy loads or overload, you will need them at a much higher psi, and they will wear faster in the center, and never be as strong/safe to reach their maximum load capacity, i.e. don't do it on your 1 ton, unless it's just a daily driver.

A lot run the shorter 325/60R18 Nitto Terra Grappler A/Ts on the stock rims, and love them. But I do recall seeing a couple of the taller LT325/65/18, level kit, stock wheel threads on here.

IMO, even though the 35's will fit with trimming, the 33's are a better match. Even with the lower BT/OR gears, I notice changes in the torque converter locking up properly with my new 33.98" A/Ts, while my previous 33.5" Toyo M/Ts dropped the rpms down to 1500-ish right away once reaching 55 mph, these will hang the rpms at something like 2200 much longer, or until I notice and momentarily and let up on the gas pedal.

Maybe once a Titan crosses that line, it doesn't get any worse, say for mine, maybe a 36.5 might act the same as my 34s, idk. I've heard of this with 34.5" tires but thought I was going to be o.k. Not a big deal, but basically I need gears, and they don't have them yet for the 4x4s, although they are supposed to be out soon. But I'll most likely just go with a LT295/70R17 33.5" M/T or 33.2 A/T, next time. Just something to consider with taller tires.

silverstar · 01-10-2010, 01:51 PM

I'm not too worried about the load capacity because I really don't tow much (at least nowhere near the max tow rating) and rarely have anything more than about 700lbs in the bed. The main reason i'm set on 35's is that I need tires asap as my stock crapyears are shot and are downright scary as hell in the rain and I plan on getting my procomp 6" lift later this year. So I don't want to get new 33's now and then have to get 35's to fit after the lift later this year. Not to mention I kinda actually like the look of big 35's stuffed under a mini lift. Call me crazy i guess.

NorCal 4x4 · 01-10-2010, 02:11 PM

Yeah, gotta have 35s for the 6" lift.
I wonder if the Toyo LT285/75R18 will seem too narrow on the 6" lift and stock rims. Being a M/T they might look aggressive enough, and would probably hydroplane less than a 325.

silverstar · 01-10-2010, 05:17 PM

Yeah the Toyo's are awesome for sure but I can get the firestones for about 400 less than the toyos and that's a lot of mod money I can spend elsewhere like on the 5100's. The Firestone have really good reviews for wet weather and not hydroplaning. Also I am going to sipe them to help with wet weather and ice traction as my wife and I are moving to pa this summer. I agree with you definetly that the toyos might look a little narrow and the 325s would look super beefy under there! Thanks again for helping norcal. I knew if anybody would know about this it would be you.