Wedge Wheels and Tires?

What are the biggest wheel and tire combo (width and height) that will fit under a 7 or 8 without cutting? Will roll the wheel arch... Assume a stock spring.... 235/45-17? Or?

The widest tire you can fit without serious fender rolling is a 205. The tallest tire is around 22" if you maintain the stock front spring perches. If you go to coilovers with much shorter front springs, and do away with the stock front spring perch you can go as tall as 24". Your cost effective tire wheel combo is 15X6 or 15X7 with 205/50/15 tires. The problem you will run into is the funky 4X95.25 wheel bolt pattern. The cheapest set of wheels in that pattern will run you $600 plus shipping. You can change the bolt pattern either by redrilling the lug holes or by means of wheel adapters and run much cheaper 4X100 wheels. You don't necessarily want to go bigger. Bigger is heavier with more mass farther away from the axis of rotation. In short this means it requires more HP to spin a bigger wheel than it does to spin a smaller wheel, and in the end you suffer on acceleration. You won't gain any cornering speed with the bigger tires because you have a limited contact patch of 205. TR7s run faster lap times with 185 tires because they offer less rolling friction than does the 205. You have to remember that a TR7 is limited in the HP department more than any other area. You have to everything you can to make sure you are not robbing HP before it gets applied to the road. If I was going to run a TR7 in any form of road racing, I'd use a 3.90 gear and stock TR8 alloys with 185/70/13 tires, or I'd redrill the hubs and go find a bunch of Miata 14X6 or 15X6 wheels, add a small spacer, and use either 185 or 195 series tires. Final decision would come down to how many wheels I need and what tires are available in the sizes I would choose to run.

VTO is having their Black Friday sale right now, last two days, today and Friday. CLassic 8 silver 15x6 +24mm offset, 4x95.25 (4 x 3-3/4") bolt pattern, comes with center caps, Triumph center cap logos, lug nuts and valve stems, sale price $569.60 for a set of 4.

I'm looking at a brake option that will require a least a 16" wheel. If the weight of the car was 2000lbs and the bhp was just shy of 200. Would that change your thoughts on tire width?

What kind of racing allows you to change the engine but not the rear end? If you think you are really going to get 200HP, then yes, 205 or 225 would be the tire of choice. How exactly are you going to get 200 HP in a TR7? Buick V6, Rover V8, turbo? You still don't want to go bigger just because bigger is better. Don't loose site of the fact that it is a small light car. Whatever brake option you are looking at not only sounds expensive, but it is overkill for a 2000 pound car. You will have a very very hard time finding wheels bigger than 15" in the stock bolt pattern. Stock TR8 brakes will wo that thing down over and over all day long. Minimum race weight in my TR8 was 2610 pounds. The brakes worked hard, but never let me down. Use some Capri, Volvo, or BMW calipers calipers up front just because pads are much cheaper. You can convert the stock rear end to disc brakes if you want to spend money. You need to figure out how much you want to spend and then figure out what the most cost effective way to going fast is within that budget. The stuff you are talking about wanting for this car costs more to do than going out and buying a decent TR8. What is your budget? By the time you cage the car, buy safety equipment, a couple sets of wheels and tires, bigger brakes, modest suspension goodies, you are already bouncing off 10 grand. I'm about to build another cage in a TR8. Just the materials are going to cost $700. If I had to pay someone to build it, I could expect to pay another 2 to 3 grand.

It is a TR8... Actually it’s a 1978 TR7/ V8 Coupe. So there is no engine change... The actual weight of the car is 2358lbs before I took all the interior out. (via scales at the recycler) Now it’s around 2000lbs once I add a roll cage back in the car it will add 150lbs. So let’s call it 2300lbs. The engine is a typical 3.5 no smog, headers, edelbrock intake and carb. I might put a cam in and do some head work, but I have to check the rules. (Racing series is value based for add ons and modifications) I already have modified hubs to allow for 4x100 so finding cheap wheels is no issue. I want to go with viper front brakes, it is a very easy swap and they are only $300. Ive not seen the BMWs used before. 17" aftermarket wheels that some kid took off his honda civic are all over craigs for $150-200 with half used tires. I am just looking for a size.

Todd, as you know racing means different things to people who don't do it FWIW, NASA in in the South East now has this outlaw vintage racing class now, originally designed for guys with American muscle cars who wanted to run bigger tires and brakes, than vintage, or even SCCA racing would allow. They attract all sorts of oddities, 240Z cars with wings and LT1 V8s, that sort of stuff. Those guys "almost" lap around CMP as fast as my 1800cc legal vintage race MGB

Good point Hap. I remember years ago running a race weekend at Lime Rock the same weekend that the Nascar Busch North cars were there. The test day prior to the weekend race was full of us regular SCCA cars and a handful of the V6 powered Busche cars. Their was an EP MGB running identical lap times to the Busche cars. Man those Busche cars were fast and loud in a straight line but total pigs in the corners. What I said about tire height still applies. Use whatever size rim you want to, but your tire height still has to fit under the front spring perch on the strut. If it were me, I'd go find a decent 10.5" or so vented 4X100 rotor that slips over the studs, instead of mounting to the back of the hub like the stock TR7 brake rotor. The extra thickness of the rotor hat between the hub face and the wheel face will make up some of the extra distance you will need to run 4X100 wheels, which predominantly are found cheap in front wheel drive offsets. Then use the caliper that goes with those cheap vented rotors you find, and just fabricate intermediate brackets. Then on the rear, I'd use solid discs of the same size or slightly smaller than the fronts, and their corresponding calipers with fabricated brackets. Whatever brake kit you decide to go with, you will need to size the master cylinder appropriately to work with the larger piston bores in your new brakes. Probably going to end up with a 1" master.

tr7andtvr said:

17" aftermarket wheels that some kid took off his honda civic are all over craigs for $150-200 with half used tires. I am just looking for a size.

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17" rims are WAAAYYY too big for the TR7/8. I went with 16" rims last spring, with 215/55-16 performance tires. They are a real pain. Virtually no clearance at the rear of the wheel wells. And, I rub on the front wheels front edge of well, when backing up in a turn (e.g. out of the driveway). I had to trim away at the bottom of the wheel well to stop the rubbing.

I am now looking for a set of 15" 4x100 rims with a set of 205/55-15 tires, to replace them.

Save yourself some grief and stick with 15" rims.

Here is a pic with the 16" tires: https://farm3.staticflickr.com/2847/9137094358_baeca27509_c.jpg

M.

Bsam21- Did you roll the wheel arches?

Looking at evo rotors with viper calipers. The early LR discovery master looks very similar to the Tr7/ Tr8, wonder if that can be a good swap.

tr7andtvr said:

Bsam21- Did you roll the wheel arches?

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Yup. And it isn't the easiest to roll, as the lip is already a sandwich of the outer fender and inner well sheet metal edges. And, it's much thicker metal than modern vehicles as well. In addition to rolling, I had to use a body hammer and dolly to finish it off.

Then, when I remounted the wheels, I decided that the wheels and tires looked way too big for the body, so added fiberglass arches to give it a better look.

M.

Or you could stay a little closer to home and upgrade to 15" rims....

tr7andtvr said:

Looking at evo rotors with viper calipers. The early LR discovery master looks very similar to the Tr7/ Tr8, wonder if that can be a good swap.

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The dico MC is a common swap